Some reports on the simultaneous presence of chronic idiopathic thrombocytopenic purpura (ITP) and pernicious anaemia (PA) may be found in the literature. However, little is known about the coexistence of these autoimmune disorders. For this reason, we studied the prevalence of PA in a series of patients with a diagnosis of chronic ITP by means of the analysis of the concentration of the most sensitive marker of type A atrophic (autoimmune) gastritis, serum pepsinogen I. Serum pepsinogen I was low in 20.3% of the 133 patients studied. Gastrin was elevated in 15. 2% of patients, but the coexistence of both abnormalities was rather low (7.6% of patients). However, the progressive decrease in serum cobalamin as biochemical abnormalities related with atrophic gastritis appeared was noticeable. The time to progression to frank PA from type A atrophic gastritis may span some years.