When requiring surgery, acute exacerbations of Crohn's disease in pregnancy have been reported to carry high maternal and fetal mortality. We report six cases. The women presented at 30, 28, 12, 11, 31 and 25 weeks' gestation and all proved to have intraperitoneal sepsis. In three, the acute symptoms were the first indication of Crohn's disease. All the women recovered and five had healthy babies; the other had a miscarriage when a colonic anastomosis dehisced. In pregnant women with Crohn's disease, the indications for surgery are the same as in non-pregnant patients. For acute manifestations we recommend removal of the source of the sepsis and exteriorization of the bowel ends.