During the period 1969 to 1985, 640 women with a confirmed diagnosis of ectopic pregnancy were admitted to Sentralsykehuset i Akershus. The case histories were reviewed for possible predisposing factors. From 1969 to 1985 the frequency of ectopic pregnancy increased threefold in relation to the number of conceptions in the same region. Until 1978 the major part of this increase was observed among women with IUCD in situ. Women who had previously undergone surgery on the uterine tubes accounted for the greater part of the increase in extrauterine pregnancies after 1976. A large year-to-year variation was found among women with neither of the above predisposing factors. However, a rising frequency of ectopic pregnancies was also observed in this group. It appears that the risk of ectopic pregnancy is greater among women using IUCD than among women using other methods of contraception.