The mean seasonal variations of the phytoplankton distribution and abundance in relation to the environmental conditions and human impact are evaluated along the Suez Canal, Suez Gulf and the northern part of the Red Sea coast of Egypt (May 2000–May 2001. A total of 200 species of phytoplankton belonging to 45 different genera were recorded. Bacillariophyta was the dominant group of phytoplankton (179 species) within 34 genera. Dinoflagellates are 18 species in 9 genera. Chlorophyta only one species; and Cyanophyta only two species. In summer at most stations the highest cell number and biomass of phytoplankton species were recorded. They were lower in winter. Physicochemical properties of surface water exhibited seasonal and local variations. Nitrate and orthophosphate concentrations varied significantly (P<0.001) between stations. The environmental factors influencing the distribution and abundance of phytoplankton were analysed using canonical correspondence analysis (CCA) ordination. The results showed a direct effect of the total nitrogen, ammonia, nitrate, silica, temperature, salinity and water pH on phytoplankton distribution and abundance.