He was accompanied by his wife, Melinda gates, co-founder of the Bill and Melinda Gates foundation.
On his arrival, he is understood to have visited the TB sanatorium at sub-urban Tambaram, where work on an anti-AIDS vaccine is underway.
Gates will be meeting DMK president M Karunanidhi this evening. He is also scheduled to meet Chief Minister Jayalalithaa, Indian IT industry captains, along with Communications and IT Minister Dayanidhi Maran on Friday.