Studies done so far in the history of ‘Maritime India’ have not helped much to understand the exact process of developments that took place in the Tamil coastal region in South India in the age of Portuguese expansion. Beginning with the year 1507 and expanding upto 1749—the present study is a serious attempt to throw light on the Portuguese presence in the Tamil coastal region with a discussion on the major issues related to their trade, its structure and functions, trends and its impact and implications on the economy of the region and its commercial topography. The author convincingly argues on the basis of the Portuguese sources that the years of Portuguese presence in the Tamil coast was a period of great economic revival and prosperity. Jeyaseela Stephen is Professor of Maritime History at Visva-Bharti University, Santiniketan, West Bengal, India.