An electron microscopic study was conducted on biopsies from 18 young hypospermatogenic patients. No signs of "tubular blockage" or "germinal disorganization" were found. The relationships between the different components of the germinal epithelium were comparable to those found in normal testes. Germ cells were often connected by cytoplasmic bridges and Sertoli cells by typical narrow junctions, which, in the case of very depleted tubules, were very extensive and of irregular outline owing to the interdigitations of the cells. Sertoli cells had normal cytologic characteristics and, contrary to the findings of other investigators in similar material, had apparently a normal amount of lipid droplets and microfilaments. In six cases, a large number of thick, banded collagen fibers substituted for the microfibrils usually found between the myoid cells in the tunica propia. The possible significance of these changes as a cause or as a consequence of the tubular changes is not yet clear.