A recent report found resolution of monoclonal gammopathy of undetermined significance (MGUS) in nearly 30% of patients upon eradication of concomitant Helicobacter pylori (H. pylori) infection. We performed serologicalal testing for H. pylori on 93 MGUS patients and 98 control subjects. Seroprevalence of H. pylori was not significantly different between the two groups, 30% and 32% respectively. A retrospective review of Mayo Clinic records revealed identical diagnosis rates of H. pylori infection (33%) by serology, breath or stool testing between patients with MGUS and those with negative monoclonal protein studies. There was no evidence of resolution of MGUS with H. pylori therapy.