Sera 17β-estradiol (E2), 11-ketotesteron (11-KT) and 17,20-β-dihydroxy-4-pregnen-3-one (17,20βP) levels and hepatosomatic-gonadosomatic indexes (HSI-GSI) were determined after exposing male C. carpio to 0.13 and 0.26 mg L−1 lead after 7, 14 and 21 days. Histological changes in liver and gonad tissues of male C. carpio were also determined. Sera E2, 11-KT and 17,20βP levels of male fish although showed differences from the control fish, these differences were not statistically significant. This was also true for the HSI values, the GSI values however, decreased on day 7 under the effect of 0.26 mg L−1 Pb. Dilatation in bile duct and sinusoids and lymphocyte infiltration were observed under histopathological examination. Low intensities of fibrosis were detected in testis tissues. Exposure to low concentrations of Pb did not cause endocrine disrupting and extensive histopathologic effects in C. carpio at the exposure periods tested.