A survey was made of the types of renal allotopia in children based on 5250 urographic examinations. The X-ray anatomy of allotopic kidney and the clinical symptoms of the conditions were discussed. The diagnostic value of individual X-ray techniques was critically appraised and the merits of renal angiography were stressed in terms of both diagnostics and the selection of appropriate surgical procedure. The inadequate terminology of allotopically displaced kidney was discussed.