The natural history of a disease describes its course without treatment. Description may be related to anatomy, pathology, changes on physical examination, symptoms of the disease under discussion, and the changes of all these parameters with time. Most information related to morphology and prostatic size resulted from autopsy series. Histological changes compatible with BPH may be present in the human prostate as early as age 30 years. The normal weight of an adult prostate is in the range of 15–20 g (autopsy specimens). The human prostate undergoes two kinds of growth: the first one is related to puberty, the second one to the development of BPH. The first increase of prostatic weight is clearly related to the endocrine changes occurring with puberty; the reasons for prostatic growth with the development of BPH are unknown as yet but seem to be related to endocrine factors. BPH rarely or never develops in early castrates. The scarce available information also shows that BPH is present at ages 70‐80 in 50‐75% of males studied. Only a fraction of those males showing benign prostatic enlargement actually become symptomatic. The natural history of the symptoms and their development in time and in relation to prostatic mass or other related factors is largely unknown. The available information on this subject is reviewed. In Europe, the symptomatology of BPH is described commonly in stages I‐IV. Death resulting from BPH is usually related to severe infection in combination with obstructive uropathy of the upper urinary tract. Death is rare and is prevented by timely treatment. BPH and prostatic carcinoma frequently occur in the same prostatic specimen. Considering the different location of both entities within the gland, their different incidence, the difference in morphology of their early manifestations within the fine structure of the prostate, and other factors suggest that both disease entities have a different etiology. The incidence of BPH and prostatic carcinoma increases steadily with age. It is likely that age‐related endocrine factors contribute to the pathogenesis of this disease. Copyright