AIM: To explore the essential characteristics of serum pepsinogen (PG) levels in Chinese people, by analyzing the population-based data on the serum levels of PG Ⅰ and Ⅱ and the PGⅠ/Ⅱ ratio, and their influencing factors in Chinese from North China. METHODS: A total of 6990 subjects, who underwent a gastric cancer screening in North China from 1997 to 2002, were collected in this study. Serum pepsinogen levels were measured by enzyme-linked immunosorbent assay (ELISA). H pylori status was determined by histological examination and H pylori-IgG ELISA. The cut-off point was calculated by using receiving operator characteristics (ROC) curves. Factors linked to serum PG Ⅰ/Ⅱ ratio were identified using a multivariate logistic regression. RESULTS: The serum PGⅠ and PGⅡ levels were significantly higher in males than in females (95.2 μg/L vs 79.7 μg/L, P < 0.01; 12.1 μg/L vs 9.4 μg/L, P < 0.01), PGⅠ/Ⅱ ratio was significantly lower in males than in females (7.9 vs 8.3, P < 0.01). The PG Ⅰ/Ⅱ ratio decreased significantly in the aged groups following the progression of gastric mucosa from normal to non-atrophic and atrophic lesions (10.4, 8.8, and 6.6, respectively). The serum PGⅠand Ⅱ levels were significantly higher in patients with H pylori infection than in those without H pylori infection (88.7 μg/L vs 81.4 μg/L, P < 0.01; 11.4 μg/L vs 8.4 μg/L, P < 0.01), while the PGⅠ/Ⅱ ratio was significantly lower in patients with H pylori infection than in those without H pylori infection (7.7 vs 9.6, P < 0.01). For patients with atrophic lesions, the area under the PGⅠ/Ⅱ ROC curve was 0.622. The best cut-off point for PGⅠ/Ⅱ was 6.9, with a sensitivity of 53.2%, and a specificity of 67.5%. Factors linked to PGⅠ/Ⅱ were sensitive to identified PG using a multinomial logistic regression relying on the following inputs: males (OR: 1.151, 95% CI: 1.042-1.272, P = 0.006), age ≥ 61 years (OR: 1.358, 95% CI: 1.188-1.553, P = 0.000), atrophic lesion (OR: 2.075, 95% CI: 1.870-2.302, P = 0.000), and H pylori infection (OR: 1.546, 95% CI: 1.368-1.748, P = 0.000). CONCLUSION: The essential characteristics of serum PG levels in Chinese are significantly skewed from the normal distribution, and influenced by age, sex, gastric mucosa lesions and H pylori infection. PGⅠ/Ⅱ ratio is more suitable for identifying subgroups with different influence factors compared with PGⅠor PGⅡ alone. AIM: To explore the essential characteristics of serum pepsinogen (PG) levels in Chinese people, by analyzing the population-based data on the serum levels of PG I and II and the PG I / II ratio, and their influencing factors in Chinese from North China METHODS: A total of 6990 subjects, who underwent a gastric cancer screening in North China from 1997 to 2002, were collected in this study. Serum pepsinogen levels were measured by enzyme-linked immunosorbent assay (ELISA). H pylori status was determined by histological examination and H pylori-IgG ELISA. The cut-off point was calculated by using receiving operator characteristics (ROC) curves. Factors linked to serum PG Ⅰ / Ⅱ ratio were identified using a multivariate logistic regression. RESULTS: The serum PGⅠ and PGⅡ were significantly higher in males than in females (95.2 μg / L vs 79.7 μg / L, P <0.01; 12.1 μg / L vs. 9.4 μg / L, P <0.01) females (7.9 vs 8.3, P <0.01). The PG Ⅰ / Ⅱ ratio decreased significantly in the aged groups following the progression of gastric mucosa from normal to non-atrophic and atrophic lesions (10.4, 8.8, and 6.6, respectively). in patients with H pylori infection than in those without H pylori infection (88.7 μg / L vs. 81.4 μg / L, P <0.01; 11.4 μg / L vs 8.4 μg / L, P <0.01) significantly lower in patients with H pylori infection than in those without H pylori infection (7.7 vs 9.6, P <0.01). For patients with atrophic lesions, the area under the PG I / II ROC curve was 0.622. The best cut-off point for PGI / II was 6.9, with a sensitivity of 53.2% and a specificity of 67.5%. Factors linked to PG I / II were sensitive to identified PG using a multinomial logistic regression relying on the following inputs: males (OR: 1.151, 95% CI: 1.042-1.272, P = 0.006), age ≥ 61 years (OR: 1.358, 95% CI: 1.188-1.553, P = 0.000), atrop hic lesion (OR: 2.075, 95% CI: 1.870-2.302, P = 0.000), and H pylori infection (OR: 1.546, 95% CI: 1.368-1.748, P = 0.000) CONCLUSION: The essential characteristics of serum PG levels in Chinese are significantly skewed from the normal distribution, and influenced by age, sex, gastric mucosa lesions and H pylori infection. PGⅠ / Ⅱ ratio is more suitable for identifying subgroups with different influence factors compared with PGⅠor PGⅡ alone.