This document contains the presentation by Ajay Kumar Rai, S. S. Das on paleoceanographic response of monsoonal variations in the northwestern Arabian Sea during late quaternary, presented at National climate research conference, IIT Delhi, March 5-6, 2010. This study is based on micropaleontologic and some sedimentary data at ODP Site 728A near the Oman Margin in the northwestern Arabian Sea to understand the paleoclimatic changes during last ~540 kyrs. The increased relative abundances of high fertility taxa i.e. Globigerinita glutinata and Globigerina bulloides mainly during interglacial intervals indicate open-ocean upwelling. Intense interglacial SW summer monsoon probably increased the upwelling in the western Arabian Sea and caused high surface productivities due to the lateral transport of eutrophic waters. The more stratified condition and deep mixed layer due to increased NE winter monsoon are mainly responsible for the higher relative abundances of N. pachyderma during glacial periods. Many glacial intervals are also characterized by pteropod spikes reflecting deepening of aragonite compensation depth (ACD) and relatively less intense oxygen minimum zone (OMZ) in this region due to deep sea mixing and thermocline ventilation, and the relatively less intense surface productivity during winter monsoon. The interglacial periods are largely devoid of or marked with very low pteropod abundances indicating more aragonite dissolution due to increased intensity of OMZ in the northwestern Arabian Sea. The sediment accumulation rates are lower during interglacial periods than the glacial intervals. The total biogenic carbonate percentages were, on average, higher during interglacial and during periods of higher surface productivity. Most terrigenous material is trapped on the shelf during intervals of high sea-level stands of interglacial, whereas during glacial periods this zone is eroded and sedimentation rates are higher in the upper slope basins. In addition, the fragmentation record may be the result of changes in intensity, and vertical distribution of the OMZ with time. The lower boundary of the OMZ probably during glacial intervals was in a relatively shallower depth than during interglacial periods, when organic production due to monsoonal upwelling increased. The higher rates of sinking organic matter result into a stronger OMZ as oxygen is used to disintegrate the organic matter which lowers the pH