The clinicopathologic features regarding 20 patients who had placental polyps removed, either by curettage or hysterectomy, months or years following pregnancy are described. More than half had had some type of menstrual irregularity, and abdominal pain was a prominent symptom in one-third of the group. Trophoblastic tissue was identifiable in all specimens, and in four, villi were essentially normal. Significance is attached to the apparent long-term histologic viability of such trophoblastic cells, enabling comparison with the growth potential of long-entrapped cancer cells.