The semen characteristics of 100 fertile indigenous blacks were studied. The mean semen volume was 2.6 ml, sperm density 55 million/ml, motility 61% and well-formed sperm 71%. These figures are comparable to those of similar recent studies in Caucasians but differ significantly from earlier studies. Our data seem to support recent observations that there has been a decline in the sperm density of fertile males in the past 3 decades and that the earlier standards of sperm concentration may be too high for the present.