BackgroundRoyal jelly (RJ) is a complementary diet widely prescribed by traditional medicine specialists for treatment of in- fertility. The aim of present study was to evaluate the effects of RJ on a set of reproductive parameters in immature female rats.Materials and MethodsIn this experimental study, thirty two immature female rats (30-35 g) were divided into four groups (n=8/group): three experimental groups and one control. The experimental groups received 100, 200 and 400 mg/kg/body weight doses of RJ daily for 14 days, and the control group received 0.5 ml distilled water interaperito- nealy (i.p). The treated rats were sacrificed and their ovaries were dissected for histological examination. The serum levels of ovarian hormones, nitric oxide (NO) and ferric reducing antioxidant power (FRAP) were evaluated, and the ratios of the ovarian and uterine weight to body weight were calculated. One-way ANOVA was used for data analysis.ResultsThe body weights were significantly different (P=0.002) among the rat groups, with an increase in all RJ treated animals. Uterine and ovarian weights and the serum levels of progesterone (P=0.013) and estradiol (P=0.004) were significantly increased in experimental groups compared to the control group. In addition, a significant increase in the number of mature follicles and corpora lutea (P=0.007) was seen in RJ recipients compared to the controls. A significant increase in the serum levels of FRAP (P=0.009) and a significant decrease in NO level (P=0.013) were also observed.ConclusionRJ promotes folliculogensis and increases ovarian hormones. This product can be considered as a natural growth stimulator for immature female animals.