Three infants, born of two mothers with inflammatory bowel disease who received treatment with sulphasalazine throughout pregnancy, were found to have major congenital anomalies. In the singleton pregnancy, the mother had ulcerative colitis, and the infant, a male, had coarctation of the aorta and a ventricular septal defect. In the twin pregnancy, the mother had Crohn's disease. The first twin, a female, had a left Potter-type IIa polycystic kidney and a rudimentary left uterine cornu. The second twin, a male, had some features of Potter's facies, hypoplastic lungs, absent kidneys and ureters, and talipes equinovarus. Despite reports to the contrary, it is suggested that sulphasalazine may be teratogenic.