In this study, the levels of organochlorine (OC) pesticide residues in Lake Parishan have been investigated using water, sediment and fish (Barbus brachycephalus caspius) samples as a case study to find out the extent of pesticide contamination and accumulation in the lake. Six OC pesticides namely DDT, DDE, Lindane, Endosulfan, Heptachlor and Chlordane were analyzed in four sites at four seasons. Water samples were processed using a liquid-liquid extraction technique and gas chromatograph equipped with electron capture detector (GC-ECD). Soxhlet extraction was used for fish and sediment samples followed by clean up and gas chromatograph. DDE was the predominant residue in all the samples analyzed, at the mean concentrations of 0.055 ppb, 9.84 ppb and 4.86 ppb in water, sediment and fish samples, respectively. The lowest levels of OC pesticides were related to Heptachlor and Chlordane which none of them were found in water samples. Pol-e-Abgineh and Midstream sites had the highest and the lowest concentrations of OC pesticides, respectively