In this study several therapies were administered to 124 H. pylori-positive patients and IgG antibody titers were measured by ELISA at months 0, 2, 3, 6, 12, and 18 months. Serum titers of IgG antibody progressively decreased after H. pylori eradication; We conclude that a decrease in serum titers of IgG antibody to H. pylori relatively early after completion of therapy (1 month after ranitidine or bismuth therapy is completed and 2.5 months after antibiotic therapy is completed) can be used as a noninvasive, simple, and inexpensive method to confirm H. pylori eradication H. pylori eradication in patients with peptic ulcers is associated with important benefits, such as dramatic reduction in ulcer recurrence, acceleration of ulcer healing, and a prophylactic effect on recurrent ulcer bleeding. Furthermore, eradication of the infection in patients with low-grade gastric lymphoma is followed by regression of the tumor in most cases. Therefore, choosing the appropriate diagnostic method to confirm H. pylori eradication is very important. IgG serology is a noninvasive test (it does not require endoscopy) that has been shown to be accurate in the initial diagnosis of H. pylori infection, and quantitative antibody tests also have been demonstrated to be useful for confirming H. pylori eradication. (Click here to view/order article at Pubmed)