Abstract. to elucidate the potential etiological role of rUnX3 in the development of salivary gland adenoid cystic carcinoma (Acc), we analyzed the methylation status of rUnX3 in a series of 114 Acc tissues and 3 Acc cell lines. results showed that the methylated rate of rUnX3 was 50.9 and 3.5% in the 114 Acc samples and the corresponding normal salivary glands, respectively, achieving a significant difference (p<0.001).There was a significant correlation between RUNX3 methylation and various clinicopathological parameters of Accs, such as perineural invasion, lymph node involvement, t-stage and distant metastasis (p<0.001). rUnX3 methylation was a significant predictor of the 5-year disease-free survival in ACC patients after surgery. partial methylation was found in all 3 Acc cell lines, and the reactivation and more potent expression of RUNX3 was induced by 5-triazole-2-deoxycytidine. Our findings indicate that rUnX3 methylation may occur as a common event in the development of Acc and that methylation may be a major mechanism for inactivation of RUNX3 in ACC.