Latest Pliocene-Pleistocene (last approximately 2.5 myr) deep sea benthic foraminiferal diversity at Ocean Drilling Program (ODP) site 763A in the eastern Indian Ocean was examined to infer the paleoceanographic and paleoclimatic changes. Species diversity was measured in terms of Shannon-Weaver Index [H(S)], Hurlbert's Diversity Index (S (sub 100) ), and Equitability (E'). In general, all diversity parameters show almost similar pattern during the examined interval. Values of H(S) show almost inverse relation with Uvigerina proboscidea abundance, total percentages of infaunal taxa and suboxic taxa. This relationship indicates that the Pleistocene benthic foraminiferal diversity in the eastern Indian Ocean is dominantly controlled by changing trophic level due to surface productivity and deep sea ventilation. Relatively more diverse fauna during the latest Pliocene interval along with other faunal changes suggest oligotrophic deep sea condition with better ventilation of the bottom water possibly due to reduced surface productivity. The strengthening of the flow of Leeuwin Current of warm, less dense and less saline water along the offshore Western Australia was responsible for reduced upwelling and surface productivity. Less diverse fauna with several fluctuations during most of the Pleistocene Period (1.5 Ma and younger) suggest increased surface productivity due to development of upwelling system and relatively less oxygenated conditions at the sea floor.