OBJECTIVE To evaluate the efficacy of microsurgical vasectomy reversal on patients after vasectomy. METHODS In the study, 41 patients after vasectomy were admitted for microsurgical vasectomy reversal. The mean (range) age was 45 (29 to 66) years for the men. The mean duration of obstruction was 12 years. All the patients were seen by the surgeon for a complete history and physical examination. Semen analyses proved azoopermia, and their serum levels of sexual hormone were normal. They were all offered scrotal exploration. Microvasovasostomy was performed if the sperm was found in the material coming from the proximal vas lumen. The decision for microvasoepididymostomy was made during surgery, if the fluid was creamy, containing only debris or there was no fluid whatsoever when the vas was milked toward the cut end. Microvasovasostomy was performed in 40 patients, of whom 6 were with lateral microvasoepididymostomy and 1 with bilateral microvasoepididymostomy. The initial semen analysis was then done after usually 3 months postoperatively. Patency was arbitrarily defined as>10 000 sperm/mL in ejaculate in at least one semen analysis after surgery. Postoperative patency rate and postoperative impregnation rate were followed. RESULTS The 41 patients were followed up for 3 to 72 months, and 5 cases were lost. In the 28 patients who had obstructions for less than 15 years, 3 were lost. Sperm was found by semen analysis in 21 patients. Their sperm density was 2×10(6) to 46×10(6) sperms/mL and motility was 0% to 60%. The semen analysis revealed azoospermia in 2 patients after 12 months, who were advised to undergo intracytoplasmic sperm injection. Natural conception occurred in 6 patients followed for more than 12 months. The overall patency rate was 84% (21/25). Among the patients with a follow-up of >6 months, the natural paternity rate was 29% (6/21). In the 13 patients who had obstructions for more than 15 years, 2 were lost. The patency and pregnancy rates were 64% (7/11) and 14% (1/7) respectively. Their sperm density was 0.02×10(6) to 30× 10(6) sperms/mL and motility was 0% to 43%. CONCLUSIONS Microsurgical vasectomy reversal is an effective method to treat vasal obstruction due to vasectomy. The patency and pregnancy rates are related to the time of vasectomy. The patency and pregnancy rates are higher in patients with obstruction for less than 15 years than those for more than 15 years.