The aims of this study were to investigate the effects of H. pylori eradication on gastric myoelectrical activity and dyspeptic symptoms. Sixty-two subjects with H. pylori infection and no active peptic ulcer participated in this study, which involved three sessions. Anti-H. pylori therapy consisting of clarithromycin and omeprazole was given for two weeks. Gastric myoelectrical activity was measured using surface electrogastrography and dyspeptic symptoms were scored at each session. A [14C] urea breath test was performed at baseline and one month after treatment. In comparison with baseline, the percentage of normal slow waves was significantly increased and the mean total symptom score was significantly reduced one and three months after therapy (P < 0.05). Approximately 40% of patients with nonulcer dyspepsia' symptoms and H. pylori infection have abnormal gastric myoelectrical activity, which may be normalized following the eradication of H. pylori infection. The normalization of gastric myoelectrical activity may be one explanation for the significant symptom improvement in this subset of the dyspepsia population after H. pylori eradication.