Background: Nandrolone decanoate (ND) is a synthetic substance derived from testosterone and considered as an anabolic androgenic steroid (AAS). It participates in improving muscular gains associated with exercises. It could cause destructive impacts on the male reproductive system which needs to be evaluated. This study aims to investigate the effects of nandrolone decanoate on the posterolateral lobe of the prostate in albino rats at prepubertal stage and to assess the potential reversibility of these effects after cessation. Methods: Twenty-six albino rats were used, categorized into three main equal groups. Group I (control group) that was subdivided into two equal subgroups, Group II (treated group) in which rats were received nandrolone decanoate weekly by intramuscular injection (IM) in a dose 10 mg/kg for four weeks and Group III (recovery group) were received nandrolone decanoate weekly via IM injection by a dose of 10 mg/kg body weight for four weeks as in Group II followed by recovery period (without any treatment) for another four weeks. For biochemical, histological and immunohistochemical study, blood samples and tissues from posterolateral lobe of prostate were obtained. Results: Treated group showed biochemically a highly significant decrease in both serum testosterone as well as PSA and increase in tissue MDA compared to control group. Histologically, the acini were lined by flattened cells and showed weak PAS reactions. Ultrastructural examination of the same group showed nuclei of acinar cells were heterochromatic and rested on irregular basal lamina that had focal interruption and immunohistochemically, they had a negative nuclear immunoexpression for androgen receptors (ARs). However, the recovery group showed amelioration of biochemical, histological and immunohistochemical results. Conclusions: Nandolone decanonate causes significant biochemical, histological and immunohistchemical changes in the prepubertal dorsolateral lobes of the prostates and its stoppage caused remarkable improvement.