All ectopic pregnancies occurring in a defined New Zealand urban area from the years 1970 and 1984 were studied (232 cases in total). The medical records and histological preparations were reviewed. A 38% increase in the incidence of ectopic pregnancy over this 15-year period is documented. The percentage of patients with histological evidence of past tubal infection increased from 40.6% in 1970 to 61.2% in 1984. Significant increases in the number of patients with histories of infertility or past pelvic infection and of patients with operative evidence of past infection were also noted. These results support the postulate that the increase in incidence of ectopic pregnancies over recent decades is strongly associated with the increase in prevalence of pelvic infection. Tubal damage secondary to previous pelvic infection is probably the major, although certainly not the only, aetiological factor in the development of tubal pregnancies.