Abstract: Objective: To investigate the relationship between gene expression levels of urokinase type plasminogen activator (uPA) ＆ its receptor (uPAR) and biological behavior of oral and maxillofacial malignancies.Methods: The mRNA contents of uPA and uPAR in samples were quantitatively detected by cDNA mRNA dot blot hybridization. Results: The malignent tumors had greatly higher mRNA contents of uPA and uPAR than those in their relevant surrounding tissues (P＜0.01). These mRNA contents in cancer tissues with lymphatic metastases were higher than those without lymphatic metastases (P＜0.01 and P＜0.05); lymphatic metastases were mainly affected by these genes expression levels (r=0 41 P＜0.01, r=0 31 P＜0.05). T classification, differential degradation or tumor kind wasn't correlated with uPA or uPAR mRNA content. Conclusion: The overexpression of uPA and uPAR gene is an important factor in the metastases of promoting oral and maxillofacial malignent tumors. It may be used as a symbol of tumor metastasis to detect these mRNA contents.