This study aimed to investigate the impact of selenium nano form (Nano-Se) and sodium selenite (SSe) on sexual hormones and enzymatic activity of New Zealand White (NZW) rabbits at puberty. Thirty-six male rabbits and the same number of females (6-weeks old) were distributed into three groups of 24 animals (12 females and 12 males); the groups injected intramuscularly (i.m.) once a week with distilled-water (4ml) as control, 4 ml of a solution containing 90 µg/kg live body weight of Nano-Se or SSe, respectively, for eight weeks. Serum, testicles, and ovaries were obtained at the end of the experiment. Nano-Se increased (P<0.01) ovarian and serum activities of lipase, amylase, and albumin (alb) concentration, with a decrease (P<0.01) in alkaline phosphatase (ALP) activity. In contrast, it decreased ovarian tissue activity of creatine phosphokinase (CPK) and serum alpha-fetoprotein (AFP) and increased (P<0.01) serum ALP in comparison with control. Nano-Se increased (P<0.01) testicular amylase, lipase, AFP, serum CPK, and alb (an opposite trend observed in SSe treatment), with a decrease (P<0.01) of serum ALP and alb. SSe increased (P<0.01) ovarian amylase, CPK, ALP activities, alb, and serum ALP. However, SSe decreased (P<0.01) blood amylase, lipase (also in ovarian tissue), CPK, and AFP weighed to control. Nano-Se and SSe raised Se concentrations in ovarian and testicular extract compared to control. Estradiol-17β, progesterone, and testosterone increased (P<0.01) due to Nano-Se taking