Four cases of renal hemangioma are presented. Renal hemangioma is difficult to detect because this benign vascular tumor never demonstrates any abnormalities on renal arteriography. Computed tomography in two resected cases of cavernous hemangioma revealed a low-density mass without any enhance effect, while the others diagnosed by the selective renal arteriography demonstrated no abnormality on computed tomography. We postulate that both angiographic and computed tomographic appearances of the renal hemangioma could depend on its vascular components. Related reports are also reviewed.