Dr.Boon Vanasin and a group of doctors founded Thonburi Hospital Co., Ltd. with a paid-up registered capital of 20 million baht on 13 August 1976. He chose Thonburi for the hospital location as there was no private hospital in the area while the only public hospital, Siriraj Hospital, was very crowded and lots of patients had to wait for a long time due to insufficient beds. The birth of Thonburi Hospital, which was aimed to provide excellent healthcare services, met demands of the growing number of patients.

Thonburi Hospital was opened on 10 May 1977. Located at 34/1, Itsaraphap Road, Ban Chang Lo, Bangkok Noi, Bangkok 10700, the hospital started its operations as a 60 bed-hospital. Medical service were provided by respected and senior physicians from Siriraj Hospital who have shared commitment to providing quality and convenient services to upper-to-high income earners in Thonburi, or west side of the capital.

Thonburi Hospital had been well received and continued to grow to the point that the OPD clinics and beds couldn’t cope with the rising demand in the area. The building extension took place in 1980 – both vertically and horizontally. The hospital’s capacity was increased to 113 beds and its register capital rose to 60 million baht.

The company was well established and determined to deliver service quality with professional excellence, and trusted by people in Thonburi area. This rapid increase in the service demand resulted in shortage of beds. The company therefore expanded its capacity by building a new 12-storey building and opened Thonburi2 Hospital with 300,000,000 baht registered capital.

On 8 March 1993, Thonburi2 Hospital was officially opened. The new 68-bed hospital is located at 43/4 on Borom Ratchonnani Road in Taweewattana District, Bangkok 10170.

On 21 December 1994, Thonburi Hospital Co., Ltd. became a public company and was renamed “Thonburi Hospital Public Company Limited.”

The company started expanding its services through affiliated firms in the provinces. Considering the shortage of medical professionals, Thonburi Healthcare Group Pcl. joined forced with Siam University in offering undergraduate course in medicine to produce qualified medical professionals who can provide high quality service and have the ability to develop themselves and the society.

On 11 December 1997, the company acquired Dental Siam Co., Ltd. which distributes dental products and operates pharmaceutical shop business.

Thonburi Healthcare Group Pcl. entered into an agreement to directly operate Provincial Administration Organization (PAO)’s hospital in Phuket, the first PAO hospital in Thailand with 129 beds.

Thonburi2 Hospital opened its second building on 1 June 2012 to cope with the increasing demand. The two buildings have a combined capacity of 95 beds. The company also signed an agreement to operate and manage the 110-bed Pattaya City Hospital.

The company raised its registered capital to 600 million baht on 10 May 2013. The company, in collaboration with Siam University, offered medical science course for the Faculty of Medicine to train and produce qualified and ethical physicians, which addressed the shortage of doctors in the country.

6 January 2014, the company bought a 31.87% stake in Sirivej Chantaburi Pcl. whose registered capital is 585 million baht.

16 July 2014, the company set up a subsidiary called the Thonburi Hospital Heart Centers Co., Ltd. to provide specialized medical and management services to other hospitals by establishing a new or being an integral part of such hospital’s heart center. Thonburi Healthcare Group Pcl. holds 70% shares in the subsidiary with a registered capital of 100 million baht. The subsidiary currently operates the heart centers for Phatara-Thonburi Hospital and Bang Phli Hospital in Samut Prakarn province.

22 september 2014, the company acquired additional shares in Modular Software Expertise Co., Ltd., raising its stakes in the company to 70% of 18 million baht in registered capital.

20 October 2014, the company set up Premiere Home Health Care Co., Ltd. to provide healthcare service at patient’s home and to build a stand-alone elderly care facility. Thonburi Healthcare Group Pcl. holds 99.99% share in the new company with a registered capital of 100 million baht.

15 December 2014, the company acquired 100% stake in Rajthanee Realty Co.,Ltd. with registered capital of 700 million to operate a real estate business and to handle land plot allocation in the elderly care service project.

24 December 2014, the company took over a property firm, Thonburi Real Estate Development Co., Ltd. Thonburi Healthcare Group Pcl. holds 99.78% stake in the 800-million-baht company.

30 December 2014, the company increased its stake in Ubonrak Co., Ltd (Ubonrak Hospital) to 34.04% of the 37.5 million baht registered capital.

2 April 2015, the company acquired stakes in Rajyindee Hospital Pcl., raising its capital to 54.23% of the 400 million baht registered capital. 16 November 2015, the company increased its stakes in Thonburi Hospital Heart Centers Co., Ltd. to 99.98% of the 100 million baht registered capital.

1 January 2016, the company has contract with Wego Holding Company Limited to set up a “Joint venture” in the name of “Weihai Thonburi Medical Equipment Company Limited” which has an objective to provide hospital operations in People’s Republic of China (“Welly Hospital”) with registered share capital amounting to Renminbi 230.00 million (equivalent to Baht 1,249.00 million). The Company held 58% of registered share capital.

17 February 2016, Rajyindee Hospital Public Company Limited decreased in registered shares from Baht 400,000,000 to Baht 388,271,118 by deducting the unsold registered shares in order to maintain the remaining registered share capital at the paid-up share balance. The registration to decrease of share capital resulted in the change in the Company’s shareholding from 54.23% to 55.87%.

26 February 2016, the joint venture has registered to change its name from “Weihai Thonburi Medical Equipment Company Limited” to “Weihai Thonburi Healthcare Investment Company Limited”.

29 June 2016, the Company has increased its registered capital to Baht 849.08 million (paid-up capital of Baht 764.08 million) to support the initial public offering (“IPO”).

30 August 2016, the Company purchased additional shares of Premier Home Health Care Co., Ltd. of Baht 850 million, resulting in the increase of registered and paid up share capital of Premier Home Health Care Co., Ltd. to Baht 1,150 million. The Company’s shareholding remain at 99.99%.

4 April 2017, the Company, Ga Mone Pwint Co., Ltd., Ar Yu Ananta Medical Services Co., Ltd. and WJ International Hospital Management Co., Ltd. to set up and register a "Joint venture" named “ARYU International Healthcare Company Limited” which has an objective to provide hospital operations in Republic of the Union of Myanmar (Ar Yu International Hospital), with registered share capital amounting to USD 100.00 million (10,000,000 ordinary shares at par value USD 10.00 each). The Company held 10% of registered share capital. The joint venture called-up 50% of registered shared.

1 June 2017, the Company entered into a consultancy contract and conducted a comprehensive study (Consultancy and Comprehensive study) for private hospitals of King Saud University, Riyadh, Saudi Arabia. This project is the collaboration between InterHealth Saudi Arabia Limited (a subsidiary of InterHealth Canada Limited) with the Company. The Company is contracted to provide consultancy and implementation of general hospital management. This is a preliminary cooperation. The total value of the project is about USD 2.8 million.

31 May 2017, Rajyindee Hospital Public Company Limited increased in registered share capital from Baht 388,271,118 to Baht 430,000,000. The Company added investment in the ordinary shares of Rajyindee Hospital Public Company in Baht 83,421,429. Limited, so resulted in the change in the Company’s shareholding from 55.87% to 56.91%.

1 November 2017, the Company purchased 99.99% of Bamrungmuang Plaza Limited (BMP) from Power Line Engineering Public Company Limited (PLE) and its existing shareholders. To acquire the right to lease land and buildings on the leasehold right of ownership of the Thai Red Cross Society, the purchase is considered as an acquisition of assets to develop Thonburi Rehabilitation Hospital Project (Bumrungmaung Road). The idea is to build a medical center. There is an outpatient department, such as a physiotherapy department, health care and rehabilitation department, etc., and there are rooms for rehabilitation patients.

2 November 2017, the Company attended the official hospital opening ceremony of Welly Hospital in Weihai, People's Republic of China. The Company owns 58% of the shares and is the first Thai hospital to receive medical license in the People’s Republic of China.

9 November 2017, the joint venture has registered to change its name from “Weihai Thonburi Healthcare Investment Company Limited” to “Weihai Welly Hospital Company Limited” and the Board of Directors’ Meeting of Joint Venture - Weihai Welly Hospital Company Limited, approved the increase in registered share capital in amounting to Renminbi 20.00 million, totalling Renminbi 250.00 million. The Company paid share following its proportion in amounting to Renminbi 11.60 million (equivalent to Baht 58.02 million).

15 November 2017, Thonburi Hospital celebrates its 40th anniversary. Founding and being one of the nation's leading private hospitals with 19 network hospitals nationwide. The opening ceremony of a new 4-story outpatient building.

5 November 2017, the Company has approved an increase in the share capital of ARYU International Health Care Company Limited from 10% to 40% by purchasing shares from WJ International Hospital Management Company Limited at par value. Expected to pay for shares in Q1 /2018 and it is expected that ARYU International Hospital will be available in mid-2018.

7 December 2017, the Company traded its first trading day on the Stock Exchange of Thailand. The initial public offering (IPO) of 85 million shares, using the “THG” symbol, raised Baht 3,230 million to repay the bank loans. This is the working capital of the Company.

In January 2019, a new project was launched as part of Thonburi Hospital Group (THG). It was a state-of-the-art, modern and innovative new 148-bed flagship hospital with world class doctors specializing in services such as IVF, Diabetics & Wound care, Aesthetics & anti-aging, health check-up, ENT and orthopedics combined with the latest imaging technology and Geriatric Rehabilitation.

In January 2019, a new project was launched as part of Thonburi Hospital Group (THG). It was a state-of-the-art, modern and innovative new 127-bed flagship hospital with world class doctors specializing in services such as IVF, Diabetics & Wound care, Aesthetics & anti-aging, health check-up, ENT and orthopedics combined with the latest imaging technology and Geriatric Rehabilitation.

In January 2019, a new project was launched as part of Thonburi Hospital Group (THG). It was a state-of-the-art, modern and innovative new 127-bed flagship hospital with world class doctors specializing in services such as IVF, Diabetics & Wound care, Aesthetics & anti-aging, health check-up, ENT and orthopedics combined with the latest imaging technology and Geriatric Rehabilitation.