The prostatic carcinoma and prostatic hypertrophy have recently been increasing in number in Japan too; and, an importance is being attached to the correlation between the prostate gland and the testis since the prostatic tissue is dependent mainly on the androgen.The author made a detailed study of the morphological alteration of the prostate gland and the testis on aging, and the correlation of their senile changes in the 228 cases of the male unselected consecutive autopsies from the new born babies to the 90 years of age, placing great emphasis on the basic changes up to the so-called senile prostatic disease.1) The growth of the prostate gland and the testis was very slow till the maturation stage, but became rapid from around eleven years of age and was nearly completed by the puberty stage.2) As for the prostatic nodule, the early nodule developed in 20s, while the genuine nodule developed in 30s; and, the rate of occurrence and the number increased on aging, sharply after 50 years of age. The occurrence was nearly 100 per cent at more than 70 years of age.3) The secretory function of the prostate gland was observed from 12 years of age; and, the occurrence of the same increased suddenly in the form of the prostatic calculus after the maturation stage; and, the occurrence was observed nearly 100 per cent at more than 30 years of age. The prostatic calculus increased in number and it also showed a definite tendency to the calcification on aging.4) The prostate gland of the elderly men (those aged over 40 especially) were brought about atrophic changes, topical or systemic, showing a small-sized gland, the cystic change, the catarrhal change (exfoliation of the glandular epithelium), the fibrous change of stroma and so forth; and, these changes progressed gradually on aging.5) “The adenomatous change (inclusive of the so-called small glandular proliferation)” of the prostate gland and “the proliferative change of the glandular epithelium (inclusive of the squamous metaplasia)” showed a tendency to a slight increase on aging; and, their relationship with carcinoma was not clear.6) The degenerative atrophy of the spermatogenic series, the hyaline degeneration of the tubular basement membrane, “the focal tubular hyalinization”, the degenerative atrophy of the Leydig's cell and the fibrous change of stroma of the testis progressed gradually on aging from adolescence. Further-more, the relationship between “the focal tubular hyalinization” and arteriosclerosis was inferred.7) Whereas the degenerative atrophy of the spermatogenic series and the hyaline degeneration of the tubular basement membrane showed a substantial correlation, there was observed relationship to some extent between the degenerative atrophy of the Leydig's cell and spermatogenesis on one hand, and the Leydig's cell and the hyaline degeneration of the tubular basement membrane on the other.8) The prostatic atrophy and the testicular atrophy showed a considerably high proportional relationship in degree, while the correlation between the prostatic atrophy and the morphological alteration the Leydig's cell on one hand and the number of the prostatic nodule and the Leydig's cell on the other was of a medium degree respectively. Meanwhile, the relationship between the number of the prostatic nodule and the testicular atrophy was complicated.9) Both the prostate gland and the testis showed slight changes in the acute diseases, and a comparatively high degree of changes in the chronic consumptive diseases. Generally, the influence of basic diseases on the young people was greater than that on the elderly; and, the testis was subjected to stronger influence than the prostate gland.10) The prostatic carcinoma in the series of the present study numbered 4 cases, of which 2 cases were the so-called latent carcinoma.By the above, the author clarified the morphological alterat