Background and Objective: The pit of Phoenix dactylifera contains different chemical compounds such as saturated and unsaturated fatty acids, Zinc(Zn), Cadmium(Cd), Calcium(Ca), and potassium(K). Saturated fatty acids include stearic and palmitic acid and unsaturated fatty acids contain linoleic and oleic acids which could inhibit 5- - reductase enzyme. The present study was carried out with the aim of determining the effect of phoenix dactylifera pit powder on spermatogenesis and testosterone level in adult male rats.

 Materials and Methods: In this experimental research 45 wistar male rats were divided into 5 groups of 9 including the control group receiving no treatment, the saline group receiving an equal volume of normal saline as a solvent and the treatment groups receiving 0.05, 0.1 and 0.2 mg/kg body weight of Phoenix dactylifera pit powder orally for 21 days. The results were analysed through Excell, One-way analysis of variance and t-test.

 Results: The results showed that 0.1 and 0.2 mg/kg body weight of the powder increased the testosterone level significantly compared to the control and saline groups (P<0.05), whereas no significant change was observed in serum FSH and LH levels. Likewise, the above- mentioned amounts reduced dihydrotestosterone level in treatment groups (P<0.05). Histologic exam of the testis showed an increase in sperm density in seminiferous tubules of treatment groups (P<0.05).

 Conclusion: According to the research results it can be stated that the powder of phoenix dactylifera pit has probably caused increased testosterone level and decreased dihydrotestosterone level via inhibiting 5- - reductase enzyme induced by palmitic, stearic, linoleic, and oleic acids.