Background: There are few reports on the influence of depression on benign prostate hyperplasia in rats, although studies show that many factors can affect benign prostate hyperplasia in rats. Objective: To study the influence of depression on benign prostate byperplasia in rats. Design: A randomized controlled trial. Setting and materials: The experiments were made in Animal Lab of Xuanwu Hospital of Capital University of Medical Sciences. Forty male Sprague-Dawley (SD) rats, mass 220-230 g, special pathogen free animal (SPF) without special pathogen, were selected. Interventions: All the rats were randomly divided into 4 different groups: normal control group, depression group, testosterone propionaste (TP) group, and depression & TP group. In TP group and depression & TP group, each rat was given TP 1 mg/d subcutaneous injection (TP was solved into soy oil, 2 g/L), with the injection quantity of 0.5 mL. Each rat of normal control group and depression group were injected equivalent solvent. The animal models were made in 3 weeks. Main outcome measures: Prostate quality, prostate index of rats were measured, and prostate tissues sections with HE dyeing were observed. PCNA multiplication index were calculated by immunohistochemistry method. Results: The prostate index and prostate quality in depression group, TP group and depression & TP group were significantly higher than that in control group (P < 0.05-0.01), and the prostate index and prostate quality in depression & TP group were also higher than that in simple depression group (P < 0.01). The prostate index and PCNA index in simple depression group were significantly higher than that in control group (P < 0.05). The observation by histology showed that the prostate of rats in depression group was proliferated. Conclusion: The result shows that depression can accelerate benign hyperplasia prostate to a certain degree in rats.