In an attempt to confirm the reported high incidence of raised serum gastrin levels in patients with rheumatoid arthritis (RA), gastrin concentrations were estimated in 54 patients. Only three patients (6%) had basal hypergastrinaemia. The heptadecapeptide (G17) and total carboxyl-terminal immunoreactive gastrin responses to a standard protein meal were measured by specific radioimmunoassay in these three patients and in nine normogastrinaemic RA patients displaying the same age range. The three hypergastrinaemic patients showed significantly greater and more prolonged G17 and total carboxylterminal immunoreactive gastrin responses to the meal compared with the normogastrinaemic RA patients (P less than 0.02). Two of these three patients agreed to have an acid output study (pentagastrin 6 microg/kg subcutaneously) and gastric mucosal biopsies taken for histology. Both were found to be achlorhydric and to have atrophic gastritis. This study suggests that basal hypergastrinaemia in RA patients is considerably less common than previously reported and, when present, is associated with achlorhydria. In addition, the incidence of achlorhydria in rheumatoid arthritis is similar to that found in a normal age-matched population.