Success rates are often very individualized, so these numbers are difficult to provide.  After a patient comes in with his partner and has a full evaluation, including history and physical exam, a detailed expectation of success rates can be provided. On average, at 5 years, around 95% of males will have successful return of sperm to the ejaculate. At 10 years, it’s around 80%. Even when the vasectomy interval is over 15 or 20 years, the success rates of return of sperm will be lower, but they remain around 50%.