The aim of our study was to evaluate the prevalence of ED in patients with chronicrenal failure either on dialysis or pre-emptive to dialysis. The study was carried out onone thousand of chronic renal failure male patients. All patients were subjected tohistory taking, general examination, local genital examination and evaluation oferectile function by using IIEF-5. The results showed that the prevalence of ED inCRF patients who are on dialysis (group I) was 84% while it was in pre-emptive(group II) patients 79.2%, considerable association between age and ED, hypertensionand diabetes were significant risk factors while smoking was not significant and therewas positive correlation with Hb and negative correlation with creatinine.