Abstract: An investigation was made on the influence of physico-chemical parameters on zooplankton composition of Ayyampatinam coastal region situated in southeast coast of India (Lat. 09°54’ N: Long. 79°08’ E). Quantitative and qualitative analysis of zooplankton besides physico-chemical parameters were carried out from October 2007 to September 2008. 45 species of zooplankton were recorded, Copepoda formed the major fraction (44%) followsed by other metazoans (25%), decapodal larval forms (15%), Ciliats (8%), Foraminiferans (3%), Hydromedusae (2%), Decapoda (2%) and Appendicularians (1%). Higher values of zooplankton density and species diversity were found during premonsoon and summer seasons. The seasonal distribution and abundance of zooplankton are discussed in relation to hydrographical parameters.