In a survey of 930 adults aged 35-74 years randomly sampled from the general population of four areas of Italy at different risks for gastric cancer (GC), plasma levels of pepsinogens (PGI and PGII) and fat-soluble vitamins were assayed. Pepsinogen levels were used to identify individuals with chronic atrophic gastritis (CAG). Severe CAG (PGI < or = 20 pg/liter) affected 5.8% of the population, but the prevalence rose with increasing age and declining social class. Severe CAG was 5 times more common in areas with high compared to low rates of GC. Risk also rose with increasing consumption of salted/dried fish but was inversely related to dietary intake of beta-carotene and to plasma retinol and cholesterol levels. The prevalence of moderate CAG (PGI > 20 pg/liter, but PGI/PGII < or = 2.9) was 6.3%. Moderate CAG was also related to age and social class and increased 1.8-fold in areas where GC rates were high, but was not strongly associated with diet or plasma nutrients. The authors discuss these findings in relation to those from a previous case-control study of GC in the same areas.