Two male patients with end-stage renal disease (ESRD) developed a spontaneous hemorrhage of one of their native kidneys and were referred to our institution. Symptoms included sudden onset abdominal pain, hematuria and shock. Symptoms were associated with a hemoglobin decrease. Computerized tomography (CT) was done and nephrectomy undertaken in both the cases. Histologic findings confirmed bleeding and there was no abnormality other than those related to renal insufficiency (cysts and atrophy). In chronic hemodialysis (HD) patients with hematuria, if other common causes are not identified spontaneous subcapsular or renal cyst rupture should be kept in mind. Surgery is our preferred treatment because of the diagnostic dilemma of tumors and the potential mortality of massive hematomas in morbid patients.