Aim: To investigate the risk factors for prostatic inflammation extent and infection in patients with benign prostatic hyperplasia (BPH) so as to manage prostatic inflammation more efficiently. Methods: Sixty patients with BPH undergoing TURP between September 2005 and December 2005 in West China Hospital of Sichuan University were studied. Prostate fluid (PF) was collected for the measurement of secretory IgA (SIgA) and complement 3 (C3).Prostate tissue were collected for testing bacterial 16S rDNA by real-time PCR, examining SIgA in the tissue and examining the inflammation. The possible clinical and immune risk factors for prostatic inflammation or infection were analyzed by using the logistic regression method. Results: Abnormal white blood cell count in urinalysis, prostatic infection and a high concentration of C3 in PF are the risk factors for prostatic inflammation extent (P = 0.025, 0.034 and 0.035, respectively and odds ratio [OR] = 18.269, 8.284 and 1.508, respectively). Risk factors for prostatic infection include the C3 concentration and the concentration of S IgA in PF (P = 0.003 and 0.013, respectively, and OR= 1.645 and 0.993, respectively). Conclusion: The present study suggests that prostatic inflammation is associated with urinary tract infection, prostatic infection and the activated complement and that prostatic infection is associated with the activated complement and downregulated mucosal immunity in prostates of the patients with BPH. It is also suggested that individual immune regulation should be considered in the treatment of prostatic inflammation and infection of patients with BPH.