Introduction: The prostate is an exocrine gland regulated by testosterone. This gland is target of proliferative lesions, such as benign prostatic hyperplasia and cancer, which is related to the testosterone synthesis augment. The search for anticancer natural substances capable of preventing/treating proliferative lesions has fostered interest in therapeutic properties of Pequi (Caryocar brasiliense), known to be composed of various antioxidant, anti-inflammatory and anti-proliferative substances. Thus, the objective of this study was to verify the anti-proliferative property of pequi oil in the gerbil prostate under testosterone influence. Methodology: The animals were divided into the following groups: T (subcutaneous administration of testosterone cypionate; T+P (pequi oil and testosterone cypionate) and Control (intact animals). After animal death, the prostates were collected and embedded in paraffin for Haematoxylin-Eosin stain, for histopathological evaluation, and anti-PCNA immunostain for proliferative activity analysis. Results: Morphological analysis showed presence of stratification in the prostate epithelium of group T animals, accompanied by a high number of PCNA + cells, showing a high proliferative activity. In the T + P group, the epithelium presented a pseudostratification pattern, with a smaller number of PCNA + cells, similar to the Control group, showing a decrease in proliferative activity and maintenance of the normal prostate tissue architecture when compared to the T group. Conclusion: Our results show an anti-proliferative effect of pequi oil on the gerbil prostate under the influence of exogenous testosterone. Thus, pequi oil has great potential in the prevention of prostate proliferative lesions, such as cancer.