Phytoplankton pigment, cell count and species diversity wee studied at five locations in Dharamtar Creek during September 1984 to November 1985. Chemical parameters indicated a healthy system free of any environmental stress. The water was vertically mixed except during the monsoon period and nutrients never became a limiting factore for phytoplankton production. Concentration of chlorophyll a and phaeophytin were fairly high, (av. 1.94 and 1.89 mg m sup(-3) respectively). A total of 58 general of phytoplankton comprising 46 diatoms, 6 dinoflagellates and 6 other algae were recorded from the area. Thalassiosira dominated the phytoplankton community. In the interior part of the creek blooms of Skeletonema and Peridinium were respectively observed during October-November and December. Correlation between chlorophyll a and cell count was significant while there was no correlation between phytoplankton and different physico-chemical parameters. Margalefs diversity index D varied from 1.14 to 4.93 with higher diversity towards the outer than the interior zone. In general the creek sustained a rich and diverse phytoplankton community.