A survey was conducted of 513 men aged 65 74 years living in two British towns with high and low stomach cancer death-rates. The prevalence of severe atrophic gastritis (defined as a serum pepsinogen I less than 20 micrograms l-1) was significantly higher in the high-risk than in the low-risk town (14.5% and 7.7% respectively); it also tended to be higher in the manual workers, who are known to have a greater risk of stomach cancer than non-manual workers. The manual workers in the high-risk town were particularly likely to have had a partial gastrectomy. Plasma ascorbate concentration and fruit intake were lower in the high-risk area and lower social classes, suggesting a poorer vitamin C status. There was, however, no direct relationship between ascorbate concentration and the presence of severe atrophic gastritis. These findings are consistent with the hypothesis that risk of stomach cancer is determined in two stages--a long-term effect, producing atrophic gastritis; and a short-term effect in which vitamin C is protective.