The paper forms the first report on the fish fauna of Ponnani Estuary, one of the major estuaries and fishing harbours of Kerala. The ichthyofauna is represented by 112 species belonging of 14 orders, 53 families and 80 genera. The estuary characterised by high saline water almost throughout the year was dominated by marine species. The commercial fisheries was supported mainly by marine and estuarine fonns, and clupeids, anchovies, carangids, leiognathids, croakers, mullets, gobiids and tongue-soles were the major groups collected