The clinical fertility of 1077 men investigated with sperm analysis including sperm count and semen volume during the years 1950-52 was studied 20 years later using a questionnaire, replied by 785 (72.9%). There was a significant correlation (P less than 0.01) between sperm count and number of living children, but no relation to abortions and pathological pregnancies. Furthermore, sperm count was correlated (P less than 0.01) to time interval from wish of pregnancy to pregnancy obtained. Of 53 men with sperm count less than or equal to 5 mill/ml 22.6% obtained living children compared with 52.2-63.1% living children in 730 men with sperm count greater than 5 mill/ml. Sperm count is concluded to be proper for fertility classification, and sperm count 5 mill/ml is found to be the clinically significant borderline of male infertility. There was no relation between semen volume and pregnancies obtained, however, there was a statistical relation (P less than 0.01) to time interval to pregnancy obtained. Semen volume is concluded not to be suited for fertility classification.