Helicobacter pylori infection is often associated with gastrointestinal diseases, such as chronic gastritis, peptic ulcer, and gastric cancer. After total gastrectomy, positive to negative seroconversion of the H. pylori IgG antibody assayed by enzyme-linked immunosorbent assay (ELISA) was found in 10/15 patients (67%) an average of 8.5 months after surgery. Therefore, the IgG antibody persists for a long time after total removal of the stomach in about 30% of patients. Immunoglobulin A (IgA) is a major component of the local immunity of the stomach mucosa and has a short half-life. Therefore, tissue H. pylori IgA antibodies in biopsy specimens from patients with various gastric diseases were assayed by ELISA and compared with the bacterial culture, serum IgG antibody (ELISA), and [13C]urea breath test results from 144, 170, and 123 endoscopic examinations, respectively. Positivity and negativity of tissue H. pylori IgA coincided with the culture results in 67% of the examinations, and positive IgA antibody but negative culture results were found in 23%. The coincidence of tissue IgA and serum IgG antibodies against H. pylori was 64% and that of negative tissue IgA but positive serum IgG antibody results was 36%. Positivity and negativity of tissue H. pylori IgA antibody coincided with the [13C]urea breath test results in 72%. One month after completion of treatment of peptic ulcer patients for H. pylori infection with lansoprazole and benexate HCl betadex plus amoxicillin, 6/9 (67%) patients showed positive to negative conversion of the tissue IgA antibody, in contrast to no IgG antibody seroconversion. In conclusion, the tissue H. pylori IgA antibody assay is useful for detection of local immunity against H. pylori in the stomach and during follow-up after treatment.