Of the 23 cases of renal artery embolectomy reported in the literature, the operation was successful in 13, and to this group we have added two cases of our own. The acute onset of flank pain in a patient with heart disease of a type associated with embolism should strongly suggest the diagnosis of renal artery embolism. Laboratory studies are of little aid in diagnosis. Renal arteriography is the most important study, as it both confirms the diagnosis and accurately locates the embolus, allowing the surgeon to decide whether operation is indicated. Arteriography should be done as soon as intravenous pyelography has confirmed renal dysfunction. Early diagnosis and prompt operation will undoubtedly result in salvage of kidneys which are now being lost.