Asymptomatic inflammatory prostatitis is a common pathological finding in patients with benign prostatic hyperplasia (BPH). In the present study, we evaluated the correlation between serum prostate specific antigen (PSA) level and extent and aggressiveness of inflammation in surgical specimens of patients who underwent to surgery for BPH without any evidence of clinical prostatitis. Histological sections of the prostatic tissues of 52 patients were scored for the extent of inflammation and aggressiveness of inflammation, using the four point scale designed by Irani et al. Extent of inflammation is graded from 0 to 3 according to the degree of invasion of inflammatory cells in prostate tissue. Aggressiveness of inflammation is graded from 0 to 3 according to the degree of contact or disruption of prostatic glandular epithelium by inflammatory cells. The serum PSA levels in different inflammation grades were compared. There was a significant correlation between inflammation and aggressiveness scores (r = 0.39, P < 0.01). Median PSA levels in grades 1, 2 and 3 extent of inflammation were 2.4, 5.2 and 5.7 ng/ml, respectively. There was not any significant difference between these grades for PSA. Furthermore, median PSA levels in grades 1, 2 and 3 aggressiveness of inflammation were 4.4, 4.8 and 8.7 ng/ml, respectively. There was a significant difference between grades of aggressiveness of inflammation and PSA levels. High serum PSA levels may correlate with asymptomatic inflammatory prostatitis with high aggressiveness score in BPH patients without clinical prostatitis.