This study focused on hepatosomatic and gonadosomatic index and levels of plasma 17 beta-estradiol (E-2), vitellogenin (Vtg) and total protein and determined the localization of Vtg in the liver during vitellogenesis in female Chalcalburnus tarichi, an endemic cyprinid species living in the Lake Van, Turkey. The levels of plasma E-2, Vtg and total protein in female fish increased during vitellogenesis and they are positively correlated with each other. According to the results from the female fish, the lowest levels of E-2 and Vtg were measured in December at 120.60 +/- 23.38 pg ml(-1) and 1.10 +/- 0.26 mg ml(-1), respectively. The highest levels of plasma E-2 and Vtg were in May (833.40 +/- 211.58 pg ml(-1)) and April (31.31 +/- 4.9 mg ml(-1)), respectively. The Vtg-positive hepatocytes were not uniform in liver of fishes. Generally, the hepatocytes surrounding the portal and central veins were strongly Vtg positive. These results showed that plasma Vtg levels in female fish increased during vitellogenesis related to plasma E-2 and gonadosomatic index.