The cycle of the seminiferous epithelium of the rabbit was divided into eight stages, using as criteria the shape of the spermatid nucleus, the location of the spermatids and spermatozoa in regard to the basement membrane, the presence of meiotic figures and the release of spermatozoa from the lumen. The relative duration (frequency) of Stages 1 to 8 were 27·7, 13·4, 7·3, 11·0, 4·1, 15·7, 12·2 and 8·6%, respectively. Each stem cell (Type A spermatogonium) divided to produce two Type A spermatogonia. One of these was the starting cell for the next generation, while the other gave rise to two intermediate-type spermatogonia. Three more spermatogonial divisions followed, producing sixteen primary spermatocytes from one Type A spermatogonium, as is characteristic for the bull and the ram, but unlike the rat, mouse and hamster. It was estimated that only 3·1 spermatids were generated from one primary spermatocyte, suggesting that in the rabbit there is considerable degeneration of spermatogenic cells during the two maturation divisions.