Phytoestrogens are natural compounds with the potential to elicit negative effects on the endocrine systems and reproduction of aquatic life. In this study, the effect of Genistein and β-sitosterol on some reproduction indicators of Caspian Kutum (testosterone, 17β-estradiol, aromatase and EROD) were studied. A total of 49 none-ripened Kutum’s exposed to 3 different levels of Genistein and β-sitosterol (10, 50, 500 ng/l respectively). After 21 days, serum, liver and ovary were sampled and mentioned parameters were measured according to exist protocols. The result showed high level of Genistein lead to increased 17β-estradiol and aromatase activity. Also, treated fish with β-sitosterol showed high level of testosterone and EROD induction. While, both of them had no significant effect on Ca⁺⁺ level. According to this study, high concentration of Genistein (500 ng/l) could act as a stimulant endocrine system and might cause changes in steroid hormone levels and aromatase activity. It was also found that the same concentration of β-sitosterol could induce EROD activity and increasing testosterone level. It could alter biosynthesis of sex hormones and disrupt the function of endocrine system. It seems that these compounds could effect on the endocrine system of Kutum and reduce reproduction performance of Kutum in the long period.