In the present study, we investigate the steroid levels in the seminal plasma of Persian sturgeon in order to obtain the basic information about steroid changes in surrounding liquid of ejaculated spermatozoa. In this regard some steroids were measured by Radio Immune Assay (RIA) including: Testosterone (T), Progesterone (P), 17α, hydroxyprogesterone (OHP) and 17β-estradiol (E2 ). According to results, the steroid values had high variations between seminal plasma samples. The values of assay steroids were significantly lower then their concentrations in serum. T had highest concentration while E2 showed lowest concentration in the seminal plasma. As well as, there was significant correlation between T, P and OHP in the seminal.plasma. It seems that androgens comprise the main steroids of seminal plasma of Persian sturgeon males. Probably, the concentration of steroids in seminal plasma is depending on their concentrations in serum.