A total of 16 children with Shwachman's syndrome were studied over a period of 17 years. Eight cases were detected in autopsy at 6 to 15 months; all had died of cardiac failure due to myocardial lesions. The left ventricles showed necrosis of myofibres in large areas and the pancreas was atrophic and replaced by adipose tissue. The other eight patients included two siblings of deceased cases. Only one of these showed transient cardiac failure and no significant nutritional deficiencies were found. They had steatorrhoea due to failure of the exocrine pancreas and either constant (6 cases) or cyclic (2 cases) neutropenia. The steatorrhoea improved with age. Pyogenic infections, mainly otitis media were frequent during the first three years of life. Measurements of humoral and cell-mediated immunity were normal, but in addition to low numbers of neutrophils, the neutrophilic chemotaxis was depressed in all seven patients tested. Skin lesions, hepatic inflammation, and growth tended to improve with age. The family data of the patients is consistent with an autosomal recessive trait inheritance.