Phytoplankton (0.2 mm - 2 mm) are the major primary producers in the marine environment thereby forming a basic link in the marine food web. They are categorized into different groups depending on their size range. Cells in the size range of 0.2 to 2 mm are known as picoplankton which are the smallest known component of the phytoplankton community. Since its discovery in 1988, vast amount of information has been collected on picoplankton in the world oceans which shows that these organisms most often dominate the photosynthetic biomass. The picophytoplankton comprises of two cyanobacteria, Prochlorococcus and Synechococcus and a range of picoeukaryotes. The Arabian Sea and the Bay of Bengal are the least explored areas in terms of picoplankton distribution. Although there are reports of picoplankton from the western Arabian Sea, there is no detailed information available on the distribution of different picoplankton groups from the eastern Arabian Sea. Observations on picophytoplankton groups and their abundance are underway from Dona Paula Bay and Bay of Bengal through flow cytometry. Some highlights from these observations are presented