Spontaneous retroperitoneal hemorrhage is an uncommon affection, the diagnosis was recognized by sonography and CT scan, but the etiology remains unknown and exploration for diagnosis may become necessary. In the absence of an apparent etiology, patients with spontaneous renal bleeding should undergo radical nephrectomy, because of the extremely high incidence of small undetectable occult tumors. Three further cases were reported by the authors, who made a review of the literature.