Meconium causes difficulty only when it is not expelled from the intestine of the newborn infant within a day or two of birth. Meconium peritonitis is a sterile chemical peritonitis occasioned by an intrauterine perforation of bowel. Calcification always results, and usually is visible on roentgenograms of the baby’s abdomen. As a rule meconium peritonitis occurs in association with intestinal atresia and requires surgical treatment. Meconium ileus is the earliest clinical manifestation of cystic fibrosis of the pancreas (which in approximately 10 per cent of cases provides the presenting symptoms). Unless diatrizoate enemas remove the abnormally thick and tenacious meconium from the bowel, surgical treatment is required. The meconium plug syndrome is the commonest and least serious disorder related to meconium in the newborn. Some infants require assistance in expelling the meconium, but after elimination of the plug they are perfectly normal. Kotileus is a term we consider possibly more usable than meconium-ileus equivalent to designate a late complication in some patients with cystic fibrosis. If administration of pancreatic enzymes fails to relieve the obstruction, the radiologist may succeed with diatrizoate enemas.