Residues of organochlorine pesticides (OCPs) were detected in water, sediment and liver tissue samples of the common carp (Cyprinus carpio Linnaeus, 1758) collected from the Ataturk Dam Lake. Ethoxyresorufin O-deethylase, glutathion S-transferase, glutathion reductase, superoxide dismutase, catalase and carboxylesterase activities have been evaluated in liver of Cyprinus carpio. The level of OCPs were determined by Gas Chromatography-Mass Spectrometry. No pesticide residue was determined in the water samples and residues in the sediments were higher than in the fish. In the wet season, the level of pesticides were higher than in the dry season. The concentrations of OCPs were highest in the Akyazi and Bozova areas. Enzyme analysis results showed that the activities were different from region to region and generally higher in Akyazi and Bozova than the other areas. This study is the first study that determines the levels of OCPs of sediment, water and fish in Ataturk Dam Lake and presents pesticide residue levels in the fish samples were above the maximum residue limits so could be a threat to the human health. The presence of OCPs indicates the need for continuous monitoring of the Lake fish population to safeguard the health of the consumers.