A retrospective study of 83 patients with pathologically documented tubal ectopic pregnancy demonstrated a statistically significant association (P less than 0.005) between prior spontaneous abortion and ectopic pregnancy. In this population with a low incidence of chronic salpingitis, it is suggested that delayed (post-midcycle) ovulation, causing preovulatory over-ripeness of the ovum, may be the common underlying etiologic factor. The clinical significance of this finding is also briefly discussed.