Abstract
A man with crossed, non-fused renal ectopia had carcinoma of the distal ureter, leading to hydro-ureter, hydronephrosis and urinary infection. Crossed ectopic kidneys are more disease-prone than are normal kidneys. Complicating disorders are discussed, the value of thorough urologic investigation is stressed and the incidence of tumour of the upper urinary tract in crossed renal ectopia without fusion is reviewed.