目的　探讨口腔粘膜癌变过程中CK19的变化。方法　收集正常口腔粘膜、上皮单纯增生、上皮异常增生和口腔鳞癌活检标本共 5 3例 ,用免疫组化、电泳和Western杂交方法研究上皮中CK19的表达。结果　CK19表达于有上皮异常增生的复层鳞状上皮基底上层和口腔鳞癌尤其是低分化鳞癌的癌细胞中。随病变程度加重 ,CK19表达的阳性率、表达强度和占细胞角蛋白的构成比显著增加。结论　CK19表达于口腔粘膜上皮的基底上层可作为口腔癌前病变的辅助标志 ,CK19表达增加是口腔粘膜癌变过程中的早期事件 Objective To investigate the changes of CK19 in the process of carcinogenesis of oral mucosa. Methods A total of 53 specimens of normal oral mucosa, epithelial hyperplasia, epithelial dysplasia and oral squamous cell carcinoma were collected. The expression of CK19 was examined by immunohistochemistry, electrophoresis and Western blotting. Results CK19 expression in epithelial dysplasia of the stratified squamous epithelium and oral squamous cell carcinoma, especially poorly differentiated squamous cell carcinoma cells. With the severity of the disease, the positive expression rate of CK19, the expression intensity and the ratio of cytokeratin constitute a significant increase. Conclusion CK19 expression in oral mucosal epithelium of the basal layer can be used as a secondary marker of oral precancerous lesions, CK19 expression is an early event in the process of oral mucosa carcinogenesis