Fundic argyrophil cells were studied for a mean period of 68.7 months (range, 11-170) in 18 patients with fundic atrophic gastritis and achlorhydria. Initially, 12 patients had hyperplasia of the argyrophil cells, the severity of which was assessed using a semiquantitative classification based on the number of argyrophil clusters per square millimeter. At the end of the study, the degree of hyperplasia was unchanged in 9 patients, had decreased in 2, and had increased in 1; no significant increase in the number of argyrophil clusters, precarcinoid changes, or carcinoid tumors were observed and the high level of gastrinemia [mean, 4.8 (range, 1.9-8.1) times the upper limit for normal) did not change significantly. Of the 6 patients with no hyperplasia at the outset of the study, 4 continued without hyperplasia and 2 presented a low-grade hyperplasia at the 20th and 130th month. Gastrinemia increased significantly in the last patient and stayed normal in the other 5. This study argues in favor of the stable appearance of fundic argyrophil cells in patients with atrophic gastritis and stable gastrinemia.