Two species of Cladocera, 9 species of Ostracoda, 13 species of Chaetognatha, 20 species of Pteropoda, 10 species of Heteropoda and 4 species of Thaliacea were collected from the upper 200 metres of the sea area from Java Island to the north-western Australia (ca 10°S-30°S, 105°E-120°E) in two successive winters (of the northern hemisphere) in 1962-1963. The area can be divided into two regions by water masses, the area north of about 17°S under influence of westward current (A), and the area of northward flowing West Australian Current (B). Most of the zooplankton species are widely distributed in both regions, but some of them are confined in either region A or B.