Abstract The lipids and fatty acids composition of the black oyster Pteria colymbus were determined during three year seasons (transition, raining and dry) between October 2006 and August 2007, using automated Thin Layer Chromatography (TLC/FID-Iatroscan) and Gas Chromatography, respectively. The lipid content ranged between 1.19 and 3.44% with the maximum value for the samples collected during the dry season. Phospholipids were higher (85.1-89.2%) than triacylglycerols (5.4-12.8%) and cholesterol (2.2-6.6%). The unsaturated fat content (41.17- 70.57%) was higher than saturated fat during transition and dry seasons. Saturated fatty acids showed the highest concentration (52.48%) in the rainy time with palmitic acid (31.32%) as the main component. Among the unsaturated fatty acids, polyunsaturated compounds were in