A study on the seasonal variations and species association of the meroplankton from the Palk Bay and the Gulf of Mannar biosphere reserve areas along the southeast coast of India during October 1993 and November 1995 was undertaken. The results indicated that the water quaIity differed between the two stations. The number of meroplankton reached maximum by October-December and gradually decreased during June to August. The average number of meroplankton was highest in Palk Bay. The meroplankton was constituted by the larval stages of commercial penaeids such as Penaeus sernisulcafus. P indicus, P. monodon, P. meuguiensis, Metapenaeus monoceros, M. dobsoni and M. affinis; zoea and megalopa of crabs, veliger larvae of gastropods and bivalves; and the fish larvae. The veliger larvae of gastropod and bivalves constituted 66% of the total rneroplankton.