Distribution and abundance of major groups of mesozooplankton of the upper 1000 m of the Andaman waters, during winter monsoon (December 2003–January 2004) is described based on collection made from a ship. Stratified samples were collected from five standard depths using Multiple Plankton Net (MPN). The quantitative and qualitative abundance of mesozooplankton were found to be maximum in the mixed layer. The average zooplankton biomass in the mixed layer was 243 ml per 1000 m3, which was a high value for the season. Zooplankton abundance and standing stock showed spatial and temporal variations. The average biomass was higher on the eastern side of the Island chain than on the western side. Areas of high zooplankton standing stock were encountered in the 12°N latitude area. Copepods (84.5%) formed the dominant group, followed by chaetognaths (6.9%), ostracods (2.5%), decapods (1.9%) and copelates (1.6%). Distribution and abundance of zooplankton were influenced by various hydrographical characteristics. Comparatively higher values of dissolved oxygen, primary production and chlorophyll-a were noticed in the mixed layer on the western side.

 Meso-zooplankton, Andaman sea, winter monsoon, Mixed Layer Depth.