A rare case of intrathoracic kidney was reported. A 71-year-old female with no complaint presented for evaluation of an abnormal shadow in the left lung field. A routine chest roentgenograms showed a sharply outlined mass in the postero-medial portion of the left lung field. Computed tomography demonstrated left intrathoracic kidney with anomalies of rotation. Intravenous pyelography demonstrated a left high ectopic kidney with complete duplication of the renal pelvis and incomplete duplication of a ureter. The patient was diagnosed as left intrathoracic kidney with renal anomalies. The 79 cases of intrathoracic kidney reported in Japan were analyzed concerning their etiology.