Objective:To evaluate the effects of Xiaojin Pill (小金丸) in the treatment of Peyronie\'s disease (PD) in a rat model.Methods:Twenty-four male Sprague-Dawley rats were randomly divided into four groups with 6 in each:sham operation,PD model,vehicle control and Xiaojin Pill groups.The rats in the sham operation group received penile tunica albsginea (TA) injection with 50 μ L vehicle,while the rats in the other 3 groups received 50 μ L penile TA injection of 50 μ g transforming growth factor (TGF)-β 1.Forty-two days after the injection,rats in the vehicle control and Xiaojin Pill groups received 0.5 mL water and Xiaojin Pill solution (107 mg/kg of body weight),respectively by gavage for 28 days,while those in the sham operation and PD model groups did not receive any intervention.After intervention,the expressions of matrix metalloproteinase 2/9 (MMP2/9),nitric oxidesynthase (NOS),superoxide dismutase (SOD) and malondialdehyde (MDA) were measured.Results:Rats in the PD model and vehicle control groups presented obvious fibrosis in corpus cavemosum (CC) and demonstrated a significantly increased expressions of MMP2 and MMP9 in the CC compared with the sham operation group (all P＜0.01).In contrast,the expressions of MMP2 and MMP9 in the Xiaojin Pill group were significantly down-regulated (both P＜0.01).In addition,the levels of NOS and MDA in CC were significantly increased while the activity of SOD was decreased in the PD model and vehicle control groups compared with the sham operation group (all P＜0.01).After Xiaojin Pill treatment,the levels of MDA,NOS and SOD appeared to be corrected (all P＜0.01).Conclusions:Xiaojin Pill could reduce fibrosis in the CC by decreasing the expressions of MMPs,NOS and MDA,and by increasing the activity of SOD.Therefore,Xiaojin Pill might be a therapeutic option for PD.