Eradication of Helicobacter pylori improves clinical symptoms and quality of life in patients with peptic ulcer.To investigate the effect of eradication of H. pylori on body mass index and incidence of hyperlipidaemia in patients with peptic ulcer.The study population comprised 50 patients (42 men, 8 women; mean age, 51 years; 28 gastric ulcer, 22 duodenal ulcer) who underwent physical and blood examination before and 1 year after undergoing eradication therapy and 100 sex- and age-matched control subjects. Body mass index, total cholesterol and triglyceride were measured before and 1 year after therapy.The eradication therapy group showed a significant increase in body mass index (22.7±2.5kg/m 2 before eradication versus 23.6±2.6kg/m 2 after eradication, p<0.01), serum total cholesterol (204.1±33.2mg/dL versus 221.2±38.8mg/dL, p<0.01), and triglyceride. Additionally, the eradication therapy group showed a significant increase in the incidence of hypercholesterolemia (30% versus 58%, p<0.01), hypertriglyceridaemia (28% versus 44%, p<0.01) and obesity (12% versus 22%, p<0.05) 12 months after therapy.Our findings show that eradication of H. pylori significantly increases the incidence of hyperlipidaemia and obesity in patients with peptic ulcer.