Postmortem examination of a 26 week old (postmenstrual) human fetus delivered by Cesarean section revealed meconium ileus and many swollen mucus‐secreting cells in the gastro‐intestinal mucosa. The pancreas showed extensive fibrosis, acinar destruction and dilatation of ducts containing eosinophilic casts. Mucous glands of the lungs also revealed mucous cells swollen and distended with their secretary products. The patient is believed to have cystic fibrosis of the pancreas, suggesting that the pathologic manifestations of the disease may begin early in fetal l