Objective To investigate the cause of the positive cancer cell incisal margin in gastrectomy for gastric carcinoma. Methods Thirty-two cases with positive incisal margin in gastrectomy for gastric carcinoma from 1988-1993 in this hospital were retrospectively studied. Results The overall cancer cell positive rate (CCPR) was 7.5%, and that of radical and palliative resection were 5.5% and 12.6%, respectively (Ｐ＜0.05). The CCPR of distal and proximal incisal margin were 5.9% and 13.0% respectively (Ｐ＜0.05), which was related to the gross type, size of cancer, and the degree of differentiation and infiltration. Conclusion The CCPR is high in the infiltrating type, lesions larger than 5 cm in diameter and undifferentiated cancer. To prevent the incisal margin positive for cancer cell in gastrectomy, frozen biopsy should be done if possible.