The characteristics of the first 200 cases of vasectomy reversal have been analysed. The mean time from vasectomy to reversal was 4.8 years. It varied according to the reason for requesting reversal, and was particularly short when the operation had been performed at the time of the partner's pregnancy. Thirty percent of the men were with the same partner and 70% a new partner. Vasectomy reversal cases tended to be younger than vasectomy patients as a whole but did not differ significantly in social class. In this series of reversals, spermatozoa were present in the ejaculate throughout the 20-week follow-up time in 80% of the men; the pregnancy rate was 44%.