Although benign prostatic hyperplasia (BPH) is the most frequent disease in elderly men, not much is known in its etiopathogenesis and the factors influencing its clinical course and also the best way in its medical therapy. The inflammatory responses and immunology of the prostate have crucial roles on the three main disease of the organ. The research on the important effects of the prostatic inflammation on BPH and cancer had grown in recent years. The histological and clinical relationship between BPH and prostatitis deserves more studies in better understanding of the formation and the course of the diseases as well as effective medical therapy.