Diversity of major planktonic diatoms along the coast of West Bengal has been studied for two years (April 04-06) and their taxonomic accounts have been given. The phytoplankton population was represented mainly by diatoms, constituting more than 90% of the total population. Among the diatom genera, blooms of Asterionella japonica were observed at Junput and Digha in the month of September, Biddulphia mobiliensis appeared at Digha in April and the winter blooms of Coscinodiscus excentricus were observed at Digha Mohana and Gangasagar in December-January. Other than the blooming species, the more abundant species appeared throughout the year were, Biddulphia rhombus, Ditylum brightwelli, Cyclotella meneghiniana, Coscinodiscus radiatus and C. granii. A detailed systematic account of 19 genera and 32 species of diatoms is given in the present communication as a first phase of coastal ecological studies.