BackgroundFinding new agents for prevention and/or treatment of benign prostatic hyperplasia (BPH) especially from natural sources is a demanding field. ObjectivesThis study aimed to evaluate the effect of black mulberry (BM) (Morus nigra) fruit hydroalcoholic extract on the establishment of BPH in rats. Materials and methodsForty-nine adult male rats were randomly assigned into 7 equal groups: I: Sham control (SC), a sham surgery was performed. II: positive control (PC), rats were castrated and received testosterone propionate, at 10mg/kg/day S.C. for BPH induction. III: comparative control (CC), BPH was induced and the rats received finasteride at 5mg/kg/day P.O. IV–VII: (T1–T4): BPH was induced and the rats received BM extract at 25, 50, 100 and 200mg/kg/day P.O. for 4 consecutive weeks. ResultsFinasteride and/or BM extract especially at the two higher dosages, significantly affected prostate weight, prostatic index, percent of inhibition, serum and prostatic levels of dihydrotestosterone (DHT), serum prostate-specific antigen (PSA), antioxidant parameters of prostatic tissue as well as histopathological and histomorphometric parameters (epithelial thickness and acinar area) of prostate. ConclusionsBM extract has protective effects against experimentally-induced BPH in rats with regard to histopathological and biochemical parameters which may be related to its antioxidant as well as DHT reducing properties in prostatic tissue.