Light microscopy was used to study postcesarean section uterine scars removed at resurgery and rat urine tissues after myometrial scar simulation. The myometrial scar tissue of 1 of 30 patients and 4 of 42 experimental animals exhibited vicryl suture material remains surrounded by a connective tissue capsule and, frequently, infiltrated leukocytes and giant cells of foreign bodies. It is not inconceivable that the presence of these foreign bodies in the tissues of the uterus and its scar may lower the strength of the wall of this organ during pregnancy and labor.