Objective To study the efficiency of prostat in improving the histological inflammation of prostates and lower urinary tract symptoms (LUTS) in elderly males with moderate and severe benign prostatic hyperplasia (BPH). Methods A total of 106 patients with moderate to severe BPH/LUTS were consecutively selected into this trial and randomly divided into the control group (n=50) and the experimental group (n=56). Transurethral resection of the prostate (TURP) or transurethral laser prostatectomy was carried out in the control cases, and was done after taking 148 mg prostat daily for 3 months in the experimental cases. All the specimens were stained with both HE and immunochemistry method, and the level of histological inflammation was diagnosed by the same experienced pathologist. Results Fifty cases in the control group and 53 cases in the experimental group finished the trial. The levels of histological inflammation and cyclooxygenase (COX)-2 were positively correlated with the volumes of prostate, the international prostate symptom score (IPSS) and serum prostate specific antigen (PSA) level, while NF-κB and inducible nitric oxide synthase (iNOS) had positive correlations with the serum PSA. There was no correlation of TNF-α with the volumes of prostate, IPSS and serum PSA level. The proportions of subjects with moderate and severe histological inflammation were 37.7% (20/53) and 7.6% (4/53) respectively in the experimental group, and 52.0% (26/50) and 26.0% (13/50) respectively in control groups. Conclusions Histological inflammation of prostates may be one of the mechanisms of BPH/LUTS. COX-2, NF-κB and iNOS are the important inflammation factors. Reducing the histological inflammation could be an effective pathway to cure BPH/LUTS. Key words: Prostatic hyperplasia; Inflammation