A case of meconium ileus equivalent in a 25-year-old woman with cystic fibrosis is reported and the pathology of this condition is described. On gross examination the lumen of the terminal ileum was completely obstructed by a mass of inspissated faecal material with a putty-like consistency. The principal microscopic findings were plugging of the mucosal crypts with mucoid secretion, distention of goblet cells and the presence of a thick layer of mucus, admixed with faecal material, adherent to the mucosal surface. Mucin histochemistry demonstrated sulphomucin in the terminal ileum, although acidic mucins in the normal small intestine are almost exclusively non-sulphated.