Leaving open the testicular end of vas at vasectomy could reduce symptoms of epididymal congestion and improve the success rate of vasovasostomy but might have the disadvantage of increasing the incidence of painful sperm granulomas and spontaneous recanalization. In 4330 open-ended vasectomies the rate of epididymal congestion was significantly less than in 3867 standard vasectomies. The rate of painful sperm granulomas was not increased: it was significantly reduced. Spontaneous recanalization was rare in both groups. Whether or not open-ended vasectomy improves the success rate of vasovasostomy, it represents an improvement in technique because it reduces the rate of complications after vasectomy. Closure of the sheath over the prostatic end of vas is essential if recanalization is to be prevented.