Currently the screening and diagnosis of gastric cancer and atrophic gastritis are mainly made by endoscopy and biopsy. The aim of this study was to evaluate the use of serum tests: serum pepsinogen I (PGI pepsinogen I/II ratio (PGR), gastrin-17 (G-17) and H. pylori-immunoglobulin G (IgG) antibodies to screen atrophic gastritis and gastric cancer. A total of 458 patients were recruited, and each underwent endoscopy with biopsies before the serum tests were performed. These patients were divided into five groups based on the endoscopic and histological findings: 92 patients in the atrophic gastritis group, 58 in the gastric ulcer group, 90 in the duodenal ulcer group, 141 in the gastric cancer group (40 early gastric cancer and 101 advanced gastric cancer) and 77 (including mild non-atrophic gastritis) served as a control group. Serum samples for PGI and II, G-17, and H. pylori-IgG antibodies estimation were analyzed by ELISA. PGI and PGR values decreased significantly both in atrophic gastritis and gastric cancer groups (P<0.01). For the best discrimination of atrophic gastritis, the cut-off values of PGI and PGR were 82.3 microg/L and 6.05, respectively. The PGI, PGR and G-17 values were related significantly with the grades and/or sites of atrophic gastritis (P<0.01). Patients with atrophic corpus gastritis had low PGI and PGR values and high G-17 level, and patients with atrophic antral gastritis had low G-17 level. G-17 increased significantly in the gastric cancer group (P<0.01). PGI and PGR values were significantly lower in patients with advanced gastric cancer than in patients with early gastric cancer, while there was no difference in G-17 level between them. The positivity rate of H. pylori-IgG antibodies was 54.55% in the control group. The PGI level was higher in H. pylori positive patients than in H. pylori negative ones (P<0.001), while there was no difference in G-17 level between them. The positivity rates of H. pylori-IgG antibodies were over 85% in all other four groups. Low serum PGI, PGR and G-17 values are biomarkers of atrophic antral gastritis. Atrophic be screened by serum PGI and PGR values. Gastric cancer can be screened on the basis of increased serum G-17 and remarkedly low serum PGI and PGR values. The H. pylori infection is related to the change of PG level.