To measure the prevalence of the most common causes of end-stage renal disease (ESRD) among patients on maintenance hemodialysis (MHD), we studied the records of 248 hemodialysis patients in the Jeddah Kidney Center in December 2000. We found that the majority of cases of ESRD were of unknown etiology (42.7%). Hypertension was the most common known cause (36.3%) followed by diabetes mellitus (14.5%). We conclude that hypertension and diabetes constitute the most frequently known causes of ESRD among hemodialyzed (HD) patients in the Jeddah region.