Thirty pneumoperitoneograms were performed postmortem and 5 were performed for diagnosis: the technique itself, the radiological anatomy of the umbilical region, and the usefulness of the procedure in diagnosis are discussed. Pneumoperitoneum may be indicated in the investigation of a bleeding Meckel's diverticulum, in the exclusion or confirmation of remnants of the omphalomesenteric duct, in chronically moist lesions of the umbilicus resistant to symptomatic treatment, in suspected cases of non-communicating urachal cysts which cannot be diagnosed by cystogram, and in the differential diagnosis of abdominal tumours related to the umbilical region.