Background: Any types of pepper are widely used in traditional medicine. Secretion of pituitary-gonad axis hormones may affected by the pepper.

Objective: This study aimed to investigate the possible effects of black and red pepper on serum levels of Luteinizing hormone (LH), Follicle-stimulating hormone (FSH) and testosterone hormone was performed.

Methods: 21 male NMRI mice were divided into three groups (n=7), consisting of a control group and two treatment groups receiving red pepper and black pepper, respectively. Treated groups received pepper powder mixed with pellet food at a ratio of 6/6% for one month. At the end of treatment, animals were anesthetized with chloroform and blood samples were collected from the heart directly. After separating the serum, LH, FSH and testosterone hormones were measured by ELISA method. Data statically evaluation using one-way ANOVA followed by Tukey test for ANOVA was performed and calculated.

Results: Red pepper increased testosterone (P<0.01). Red pepper and Black pepper increased FSH (P<0.001) and P<0.01 respectively) and have no effect on the LH levels. Hematocrit levels also increased in the treatment groups (P <0.001).

Conclusion: Oral intakes of red and black peppers powder have increasing impact on FSH and testosterone hormones. Therefore, these peppers may have androgenic properties. Increases in hematocrit may be the result of an increase in testosterone.