In the present study, semi-continuous cultivation of Arthrospira platensis using various colors of light-emitting diodes (LEDs) as artificial lighting was performed in order to study their effects on the biomass composition of A. platensis. The lowest biomass productivity was obtained with blue LED (4.68 mg l(-1) day(-1)), while the highest was obtained with pink and red LEDs (30.89 and 30.69 mg l(-1) day(-1), respectively). All biomass compound contents were affected by the different colors studied, except that of total carotenoids. The lowest phycocyanin content was observed in pink LED (8.2 %) while the maximum in blue LED (17.6 +/- 2.4 %). Chlorophyll content was lowest in red LED (1.04 %) and highest in blue LED (1.42 %). The highest protein content was obtained with white and green LEDs (50.1 and 49.8 %, respectively), while the lowest was obtained with blue LED (42.1 %). Carbohydrate content was contrarily affected as that of proteins. The highest carbohydrate content was obtained in blue LED (11.3 %) and the lowest under white and pink LEDs (8.8 and 8.8 %, respectively). Lipid content seems to follow the same trend as that of carbohydrates; the highest lipid content was obtained in blue LED (6.0 %), and the lowest was obtained under pink LED (3.8 %).