PURPOSE: We tried to determine how many patients comply with semen analysis recommendations after vasectomy and how often the operation is followed by surgical failure or recanalization. MATERIALS AND METHODS: We determined the percentage of patients who underwent vasectomy from 1995 to 2003 who had follow-up semen analysis. To determine the vasectomy failure or recanalization rate, we evaluated the rates of sperm appearance in patients who were preparing for vasovasostomy and those with chronic prostatitis who had undergone vasectomy in the past. RESULTS: Among the 130 vasectomized patients, 29(22.3%) had received semen analysis, and in 120 healthy vasectomized patients, only 19(9.9%) received semen analysis. Of the 8 semen samples examined before vasovasostomy, 2(25%) had sperm. In the 121 chronic prostatitis patients, 9(7.4%) had sperm in their semen despite earlier vasectomy. Overall, 11 of 129 vasectomized patients(8.5%) were potentially fertile. CONCLUSIONS: The vasectomy failure or recanalization rate is higher than we generally think. Vasectomy failure or recanalization is usually followed by unwanted pregnancy and abortion. Unfortunately, physicians as well as patients are indifferent to the need for post-vasectomy semen analysis, and we need to emphasize its importance.