Nitrogen deficiencies were studied in Spirulina platensis (Cyanophyceae) with the aim of determining the effects of the 50 and 100% deficient nitrogen on the lipid and protein contents of the cell under laboratory conditions. S. platensis cultures were grown in Spirulina medium and kept at the constantroom temperature of 26 ± 2°C, illuminated with fluorescent lamps at an irradiance level of 80 ìmol m-2 s-1 with photoperiod 16:8 (L:D) and aerated continuously. In the Spirulina biomass harvested at the stationary phase, 67.4, 53.5, 5.6% protein and 5.78, 13.66, 17.05% lipid were recorded for the groups of control, 50% N(-) and 100% N(-), respectively. The highest lipid content and 1.00 gL-1 dry-weight were recorded from the culture to which treated 100% N(-).Key words: Spirulina platensis, lipid, nitrogen deficiencies, protein