Objective:To investigate the expression of lysozyme in ampullary carcinoma, and its relation with invasion, metastasis and prognosis. Methods: 36 cases were analyzed with immunohistochemistry of lysozyme. Results: The lysozyme-positive rate in patients with lymph node metastasis (30%) was significantly lower than that in patients without metastasis (71%), while that in patients with advanced cancer invading the pancreas (35%), was significantly lower than that in patients with cancer without invasion of the pancreas. The Survival rate of lysozyme-positive patients (66.7%) was significantly higher than that of lysozyme-negative patients (14.3%). Conclusion: The expression of lysozyme in carcinoma of ampulla is associated with invasion, metastasis and prognosis. Lysozyme is important in typing of cancer of ampulla.