Phytoplankton standing crop and species composition in Suez Bay were studied and discussed in relation to the environmental physico-chemical parameters during 2002-2003. A total of 80 species and varieties were recorded and identified at the selected stations of the bay'/Of them 47 species and 29 genera of diatoms; 19 species and 11 genera of dinoflagellates; seven species of cyanophytes within four genera; six species of chlorophytes among four genera and one species of chrysophytes. Two main phytoplankton peaks were recorded during spring and autumn seasons (average of 15,676 and 15,376 unit.!/1 respectively). The diatom species responsible of these peaks were, Nitzschia pungens var. atlantica, Asierionellajapomca, Skeletonema costatum, Chaetoceros decipiens and Gyrosigma attenuatitm. The species diversity showed a minimum value at the sewage treating company (ABB station) ranging from 2.17-3.36 nats. While, the highest diversity values were recorded at the unpolluted station, Aiyoon Mousa (VI) and varied from 2.74-3.61 nats. The results revealed regional and seasonal inverse correlation between diversity and phytoplankton standing crop in Suez Bay and it is regarded as a pollution habitat.The results of N:P ratio indicated that Suez Bay is generally P-limited, mainly due to the high load of nitrogenous compounds specially ammonia, which formed about 60.7:1 % of the total inorganic nitrogen, followed by nitrate (33.7 %) and:nitrite (5.57 %). Dissolved inorganic phosphate recorded with annual average of 0.98 pmoIX"1. Generally, the level of nutrient salts indicated that Suez Bay is in the eutrophic state.