Upper gastrointestinal (UGI) symptoms are common in uremic patients, and higher serum levels of urea have been suggested to be related to Helicobacter pylori (HP) colonization and UGI mucosal inflammation. The aim of this study was to compare HP infection and UGI endoscopic findings between uremic patients, renal transplant (RT) recipients, and controls. A total of 474 subjects (71 chronic renal failure [CRF], 73 hemodialysis [HD], 25 Tx, and 305 controls) from Baqyiatallah Hospital, Tehran, Iran were recruited between April 2002 and March 2004 for evaluation of dyspepsia, excluding those receiving any HP-eradication therapy. All subjects were examined for esophagus, stomach and duodenum mucosa, and infection with HP on 2 distinct tissue samples of the anthral region. Four groups of subjects (mean +/- 2 se; age, 45 +/- 1.6 years; 62.9% male) were studied. Duodenal ulcer in the uremic patients (CRF, 16.1%; HD, 13.7%) was more common than that in the RT-recipients (8%) and controls (6.5%); P=.038. Erosive gastritis and duodenal bulb deformity were also more common in the uremic subjects (CRF, 23.9%, 36.9%; HD, 30.1%, 20.5%, respectively) than those in the other subjects (RT recipients, 16%, 8%; controls, 8.2%; 0%, respectively); P<.001. HP infection was found to be higher in the uremic patients (CRF, 66.2%; HD, 63%) than in the RT recipients (40%) and controls (34.8%); P<.001. Higher rates of gastric and duodenal mucosal lesions and HP infection in the uremic patients in comparison with the subjects with normal renal function may have resulted from higher serum levels of urea, anemia, and fluctuations in the gastric blood supply in the CRF and HD patients. However, more tenable evidence from controlled trials is required for the eradication of HP in all uremic patients and transplantation candidates.