The aim of this work was to study the biochemical constituents of seven species of cyanobacteria namely, Calothrix fusca, Gloeocapsa livida, Lyngbya limnetica and Scytonema bohneri isolated from Panekal sulfur spring. The species namely, Oscillatoria acuminata from petrochemical refinery, O. calcuttensis from dairy effluent and O. foreaui from a sewage drain located in the Western Ghats of Southern India under laboratory culture conditions. The biochemical constituents were analyzed in terms of total carbohydrates, total protein, total free amino acid, total lipid, fatty acid and mineral contents. The analysis showed that maximum amount of total carbohydrate in S. bohneri (28.4% dry weight) and minimum in O. foreaui (8.0% of dry weight). Maximum amount of total protein and total free amino acid were in O. foreaui (7% of dry weight). O. calcuttensis showed higher amount of total lipid (20% dry weight). A total of 12 types of fatty acids were detected among which lauric acid was in highest quantity in all the seven species. Among the polyunsaturated fatty acids, oleic acid was present in all the species ranging from 1.68 to 3.89%. O. foreaui showed highest quantities of copper, manganese, ferrous and zinc. Nickel was maximum in S. bohneri (11.05 µgmL-1). O. acuminata showed highest quantity of magnesium (21.050 mg g-1) and it was least in O. foreaui (12.812 mg g-1).