Summary 1. Pneumaturia as a radiological sign is rarely noted in the urinary tract on straight radiographs of the abdomen. It is a most valuable sign requiring further radiological investigation in chosen cases. 2. Four case reports are given to illustrate the radiological aspects and problems arising from this finding. 3. The pertinent literature, pathology, and clinical aspects have been reviewed. 4. A radiological diagnostic approach to patients found to have pneumaturia has been outlined.