Vasectomy, a minor surgical contraceptive operation for men, is an increasingly popular birth control method chosen by those who plan no (or no more) children. While most of the substantial literature on the subject contains very favorable retrospective reports by vasectomized men and their wives, questions continue to be raised by some investigators about possibly adverse psychological effects both for the vasectomized man and his spouse. Unfortunately, because of methodological defects in the research in this area, there is very little definitive evidence on the psychological impact of vasectomy. We identify the flaws in most published research on the topic and suggest ethically acceptable rigorous research designs that will yield more definitive information about the psychological consequences of vasectomy. It is important to know whether vasectomy constitutes a psychological risk; it is equally important to discover whether vasectomy has the anxiety-reducing and health-promoting effects most vasectomized men report.