The species composition, diversity and distribution of diatoms present in the intertidal sediments of Gopalpur (Lat.19^O6'N & Long. 84^O 56'E) along Orissa coast in India are presented. The diatom flora comprised of a mixture of benthic-pelagic components. Out of 124 species encountered, 70 belonged to the Order-Pennales and 54 to Order-Centrales. But, only 13 pennate and 9 centric species were found as common to all the 4 locations, and thus they may be considered as endemic. The population density also showed well-marked spatio-temporal variations. There was an unexpected dominancy (86-93%) of Asterionella glarialis, during March and April. The species diversity indices - richness (D), diversity (H') and evenness (J) showed visible changes with respect to space and time.