This study aimed to provide information about the changes in fatty acid composition and quality in Ruditapes decussatus tissue after four culinary treatments (steamed, baked, grilled and fried). All treated samples showed a significant decrease in moisture and protein. In contrast, a significant increase in fat content resulted from the grilled and fried treatments. Saturated fatty acid was significantly higher in fresh clams than all cooking processes, except in fried ones. Monounsaturated fatty acid and polyunsaturated fatty acid varied significantly between fresh and cooked clams with high values recorded for fried clams. The n-3/n-6 ratio, peroxide index, EPA+DHA and atherogenicity index decreased significantly after the cooking processes particularly in fried clams. The mineral levels (Mg, Ca and Mn) of cooked clams decreased considerably with grilled and fried treatments. The impacts of cooking on the fatty acid composition and protein content in clam tissue was evaluated by lipid peroxidation (TBARS, PV, FFA, TOR) and protein oxidation (AOPP and PCO), which varied statistically in fried, steamed, grilled and baked samples; indicating alterations in cooked clam tissues structure. Based on our results, steaming is recommended for the preparation of clams because it preserves the most nutritional tissue quality.