There are plenty of theoretical advantages of two-layer microscopic vasovasostomy over one-layer vasovasostomy, but objective data are still lacking to elucidate it. One hundred and sixty two two-layer microscopic vasovasostomies were done during May 1987 to April 1989 at Seoul National University Hospital according to Silber's method, and the anatomical success rate and pregnancy rate were analysed for the 97 patients who were followed more than 18 months. Anatomical success rate of the two-layer microscopic vasovasostomy was 90.7%, and pregnancy rate was 67% which were superior to the 89%, 50% respectively of the one-layer microscopic vasovasostomy previously done at our institute. Five patients whose sperm were identified immediate postoperatively but turned to azoospermia during the follow up period, two of whom were reoperation cases, were classified as anatomical failure. Unilateral vasovasostomies were done in 32 patients whose vasal fluid showed spermatozoa and the anastomosis sites were at straight vas. Eighteen of them were followed and 17(94.4%) showed anatomical success and 13(72.2%) had impregnated. Eight patients were reoperation cases and 6 of them were followed, of whom 3 had anatomical success and 2 impregnated. These results show that two-layer microscopic vasovasostomy is superior to one-layer operation, and we expect more success will be achieved with the improvement of meticulous skill.