The authors report a case of incidental discovery of a right intrathoracic kidney in a 70-year-old man, in July 1994, on intravenous urography performed for assessment of benign prostatic hyperplasia. This intrathoracic ectopic kidney is due to a diaphragmatic hernia and may be either congenital or acquired. It must be distinguished from true ectopic kidney, present during foetal life [4], which requires a high origin of the renal artery from the aorta with elongation of the ureter. Intrathoracic kidney due to diaphragmatic hernia is usually asymptomatic, but may be responsible for severe clinical symptoms with respiratory distress occurring in a newborn infant with this malformation. The diagnosis of intrathoracic kidney must be considered in the presence of a mediastinal mass on chest x-ray and is confirmed by intravenous urography, or even thoracic computed tomography. Apart from its rare complications, this anomaly does not require any specific treatment.