Tan Tock Seng Hospital was established in 1844 through the generosity of Mr Tan Tock Seng and other 19th century local philanthropists to provide proper medical care to the sick poor. In 2001, the National Heritage Board listed Tan Tock Seng Hospital as a historic institution. This honour is for its role in providing healthcare, developing medical services and training of local healthcare professionals.

Today, Tan Tock Seng Hospital is Singapore's second largest hospital with over 1,400 beds. It encompasses the main hospital complex at Jalan Tan Tock Seng and three other campuses: the Communicable Disease Centre (CDC) 1 and 2 and the Tan Tock Seng Hospital Rehabilitation Centre at Ang Mo Kio Hospital.

Tan Tock Seng Hospital is an acute care general hospital with 17 clinical disciplines. Of these, Tan Tock Seng Hospital's distinctive strengths are in Geriatric Medicine, Infectious Diseases, Rehabilitation Medicine, Respiratory Medicine and Rheumatology, Allergy and Immunology. It is also a major referral centre for Emergency Medicine, Diagnostic Radiology, Ophthalmology (Eye), Otolaryngology (Ear, Nose and Throat), Orthopaedic Surgery, General Medicine and General Surgery.