Chalcalburnus tarichi is an endemic cyprinid species living in Lake Van, Turkey. In the present study, we investigated vitellogenin (Vtg) in the plasma of adult male C. tarichi, sampled monthly from Edremit, Campus and Carpanak sites of Van Edremit Gulf (VEG) of lake, between October 2004 and May 2005. The fish living around VEG winters in deep water around Edremit site. University and Carpanak sites are also on fish migration way from VEG to fresh water (Karasu River). The levels of measured plasma Vtg changed from trace levels to 26.35 A mu g/mL. The highest level of plasma Vtg was detected in April, with a concentration of 21.60 +/- A 1.29 A mu g/mL. We also performed immunohistochemical Vtg staining in the liver sections of male fish and determined Vtg positive hepatocytes in the liver of 1/10 sampled fish. Our results indicated that C. tarichi living in Lake Van might be exposed to endocrine-disrupting chemicals.