1). To determine the likelihood of sterilization reversal and of subsequent sterilization after sterilization reversal among men and women and 2). to examine the likelihood of pregnancy after sterilization (contraceptive failure) and of pregnancy after sterilization reversal.Payment data from the Quebec provincial health insurance system were obtained for each person undergoing vasectomy or female sterilization from January 1, 1980 to December 31, 1999 and linked through a unique identifying number for each person. Using standard techniques of survival analysis, we computed the cumulative probability of experiencing each of six events.Among women, 0.9% (of 311960) experienced a pregnancy after sterilization, 1.8% (of 321929) obtained a reversal after sterilization, 61% (of 4369) achieved a pregnancy after sterilization reversal and 48% achieved a delivery; 23% (of 4677) obtained a subsequent sterilization after reversal. Among men, 2.4% (of 310827) obtained a reversal after vasectomy and 18% (of 6694) obtained a subsequent vasectomy after reversal. All of these risks were much higher among those in the youngest age groups.Sterilization reversal and pregnancy after sterilization are not rare. Relatively high rates of reversal among the youngest age groups suggest a need for better counseling about alternative contraceptive strategies.