Abstract: Objectives In order to find out the relationship between gastric cancerous infiltrative depth and mast cell(MC) around the cancer in the elderly. Methods Bismark brown staining wethod was used for observation of MC around the cancer in 103 elderly and 72 youth patients with gastric cancer. Results Elderly cases of serosa with cancerous infiltration were less than youth ones ( P 0 01);but elderly cases of MC mean around the cancer ≥23/HPF were more than youth ones ( P 0 01). Conclusion Elderly gastric cancer with denser MC around the cancer may be one of the reasons why elderly cases of serosa with cancerous infiltration were less than youth ones.