The medics treat poor and homeless residents of the capital once a week at tables and chairs on the pavement near an ornate, century-old mosque.
The set-up has been dubbed the "Teddy Mobile Clinic" due to the free teddy bears that are given away to children -- and because it is run by a burly, six-foot (1.8 metre) tall doctor Madhusudhan Shanmugam, praised by patients for his warm, friendly character.
"With the high cost of living in the city, many people are forced to seek free medical treatment," the 35-year-old told AFP, explaining why he decided to set up the clinic two years ago in the showcase capital, home to gleaming skyscrapers and modern shopping malls.
He runs the clinic every Wednesday night. A team of doctors, pharmacists and other volunteers treat up to 40 people and distribute basic groceries like rice, biscuits and sugar, which are supplied by donors.
Madhusudhan said the patients suffer from illnesses including diabetes, high blood pressure, skin diseases and Parkinson's disease.
He said in future his team hoped to upgrade the clinic by getting a van emblazoned with a teddy bear logo that would cruise around offering treatment.