Optimal results of repair of a severed tube can be expected when a meticulous atraumatic microsurgical technique is based on a detailed knowledge of the anatomy and function of the tube. A reliable vas repair after vasectomy involves the avoidance of leakage or scarring in a tube of which the ends differ in internal diameter from 1 mm to 0-2 mm and in which the inner mucosal layer is difficult of access because of its solid muscular core surround. In addition, the healing will only occur without massive scarring and the nerve supply will only return if the blood supply can be retained as close as possible to the anastomosis. The technique described was first researched in the Macaque monkey and requires considerable microsurgical expertise. It has proved reliable in that 98% of the first 50 patients showed sperms in their ejaculates three months after operation, with a 62% pregnancy rate after an operation on one side only. The vasectomies had been performed up to 13 years before, and one can only conclude that a routine scrotal vasectomy should not be considered irreversible.