Background: The organochlorine pesticides (OCPs) are among the most commonly used in water streams around the world. Most of these contaminants are highly hydrophobic and persist in sediments of rivers and lakes. Studies have suggested that OCPs may affect the normal function of the human and wildlife endocrine systems.Objectives: The aim of this study is to determine the concentrations of selected organochlorine pesticides residues [OP’DDT, PP’DDT, alderin, dieldrin, heptachlor, (a,b,g,d) HCH, (a, b) endosulfan and metoxychlor] in samples from Karun River water at Khuzestan province in Iran, by GC-m-ECD.Materials and Methods: Water was extracted with n-hexane and then purified by passing through a glass column packed with Florisil and Na2SO4, which was then eluted with ether: hexane solution v/v.Results: In general, all of 12 investigated organochlorine pesticides (OCPs) were detected. Regardless of the kind of OCPs, the highest OCP pollution level in Karun River were seen from August to November 2009 ranging 71.43 – 89.34 mg/L, and the lowest were seen from Dec 2010 to March 2011 at levels of 22.25-22.64 mg/L. The highest and lowest mean concentrations of 12 investigated pesticides were b-Endosulfan and pp’ DDT with 28.51and 0.01 mg/L respectively.Conclusions: Comparison of total organochlorine pesticides residues concentration with WHO guidelines revealed that the Karun River had total OCPs residues above the probable effect level (0.2-20 mg/L, P<0.05), which could pose a risk to aquatic life.