An understanding of the natural history or developmental growth and clinicopathologic evolution of benign prostatic hyperplasia (BPH) is important in assessing prognosis, providing adequate treatment, and evaluating the potential usefulness of newer therapeutic agents. Currently, the general view is that BPH is basically a progressive disease characterized by different growth rates in different individuals. However, the reason for possible fluctuations in growth rate, or even that of spontaneous regression in some individuals as the result of unknown endogenous factors in the host, remains to be determined.