Serum pepsinogen I (S-PGI) and serum gastrin (S-gastrin) were examined in the screening of three types of atrophic gastritis with inherent high risk of gastric cancer: in 102 cases with severe atrophic corpus gastritis (SACG), in 5 cases with severe atrophic antrum gastritis (SAAG), and in 15 cases with severe atrophic pangastritis (SAPG) (atrophy both in corpus and in antrum) found among 916 subjects from three family series (265 from gastric cancer families, 425 from randomly selected control families and 226 from pernicious anaemia families). There is no way to screen directly atrophic gastritis restricted to the antral mucosa. In pangastritis atrophy of antral glands causes a failure of the hypergastrinemic reaction of achlorhydria. The combination of S-PGI less than 25 micrograms/l + S-gastrin less than 200 pmol/l detected 80.0% of our cases with SAPG, and only 17 subjects of 794 (2.1%) were false positives i.e. who had not advanced atrophic gastritis. The risk of gastric cancer may be significantly higher in SAPG than in SACG. The estimated prevalence of SAPG was 3% in random-family members over 60 years. The combination of S-PGI and S-gastrin is recommended when the cost/benefit ratio in the screening program of gastric cancer is considered and people from a general population are selected for endoscopic studies.