Background. Previous investigations reported that patients undergoing dialysis therapy had significantly higher serum pepsinogen (PG) levels than patients with normal renal function. However, in dialysis patients, the relationship between serum PG levels and Helicobacter pylori infection remains unknown. Methods. Sixty three maintenance dialysis patients (54 haemodialysis and nine continuous ambulatory peritoneal dialysis) who required endoscopic examination were enrolled in the study. Sixty four age- and sex-matched patients with normal renal function served as controls. We performed endoscopic examination and obtained both the gastric antral and corpus mucosa for histopathological evaluation and H, pylori identification. Twenty three patients on dialysis underwent H. pylori eradication therapy. Results. In dialysis patients, H. pylori-positives had significantly higher serum PG II levels than H. pylori-negatives (26.6+/-21.5 vs 14.1+/-7.1 ng/ml, P<0.05), but no significant difference was found in serum PG I between H. pylori-positives and H. pylori-negatives (228.8+/-158.5 vs 179.4+/-113.5 ng/ml). There was no significant difference in serum PG II between dialysis patients and controls (19.9+/-16.5 vs 18.6+/-14.9 ng/ml), while serum PG I levels were significantly higher in dialysis patients than in controls (201.7+/-136.8 vs 77.6+/-85.8 ng/ml, P<0.05). Serum PG II levels, but not those of PG I, significantly correlated with the inflammation and activity scores of antrum in dialysis patients, and these scores were highly influenced by H. pylori infection. Dialysis patients in whom H. pylori was eradicated successfully showed siginificant reductions of serum PC II levels but not of PG I. Conclusions. In dialysis patients, high serum levels of PG II, but not PC I, are significantly related to H. pylori infection and mucosal inflammation. A significant decrease in serum PG LI levels could be used as a predictor of the eradication of H. pylori infection in dialysis patients.