This article presents a meta-regression analysis of published studies of omeprazole plus antibiotics (amoxicillin, clarithromycin, or an imidazole derivative) in the treatment ofHelicobacter pylori. Eligible studies were all randomized, controlled trials published through April 1996 with 10 or more patients receiving omeprazole plus antibiotics for 5 or more days and testing forH. pylorieradication 4 weeks or more after treatment. Probability of eradication was calculated for each treatment arm, and logistic regression was performed using study characteristics as covariates. Seventy-four studies involving 117 treatment arms with 4,769 patients were identified. The eradication rate was 76% for omeprazole plus clarithromycin and 65% for omeprazole plus amoxicillin dual regimens (P< .0001). Eradication rates for triple regimens were 82%, omeprazole plus amoxicillin plus clarithromycin; 83%, omeprazole plus amoxicillin plus imidazole; and 89%, omeprazole plus clarithromycin plus imidazole. In a multiple logistic regression analysis, significant factors were antibiotic, disease, omeprazole dose, and whether treatment was followed by maintenance omeprazole. A systematic overview of the best available evidence suggests that dual therapy with omeprazole plus clarithromycin is superior to omeprazole plus amoxicillin. Triple therapy is better than dual therapy. Treatment works better on ulcers than on nonulcer dyspepsia. Higher doses of omeprazole give better results. Additional trials exploring higher omeprazole doses for varying durations as well as cost, side effects, and compliance trade-offs with efficacy are recommended.