From 1966 to 1990 there was a marked rise in the use of voluntary sterilization in Flanders, followed by a fall in women under the age of 40. In the last three decades a remarkable change has occurred in the choice between male and female sterilization. Compared with many other European countries, sterilization of men and women is widely practised in Flanders. In 1996 40% of 40- to 44-year-old women underwent voluntarily sterilization or had voluntarily sterilized partners. Additionally, another 9% of these women were sterilized for medical reasons. Voluntarily sterilized couples are on average older than non-sterilized couples, and, obviously, consider their families to be complete. For couples with a complete family, parity is the most important predictor in the choice between sterilization and non-sterilization. Regularly practising Catholics undergo sterilization least. Also, highly educated couples are less likely to have a sterilization. Couples who ever experienced a contraceptive failure choose sterilization more. Voluntary sterilization has no substantial effect on the fertility of the population since the effect on the prevented numbers of both wanted and unwanted births appears to be small. However, if voluntary sterilization did not occur, differences in fertility within the population would probably increase. It is presumed that the popularity of voluntary sterilization in Flanders has passed its peak and that its use will decline in the near future.