Objective: Mucoepidermoid carcinoma(MEC) is the most common primary malignancy of the salivary glands. Insulin-like growth factor-II m RNA-binding protein-3(IMP3) is an important prognostic factor in some cancers and a tool that differentiates between benign and malignant pancreatic lesions. This study aimed to identify a relationship between the expression of IMP3 and the outcome of salivary gland MEC, as well as to differentiate MEC from pleomorphic adenoma(PA).Methods: Tissue specimens from 70 cases of salivary gland MEC, 40 cases of PA, and 10 cases with normal salivary gland were examined immunohistochemically for IMP3. The association among the expression of IMP3, clinicopathological characteristics and patient’s survival was assessed.Results: IMP3 was present in 51.4% of MEC but absent in PA and normal salivary gland tissues. IMP3 expression was associated with age > 60 years, submandibular gland tumors, tumor size > 4 cm, high-grade tumors, lymph node metastasis, involvement of surgical margins, perineural invasion, distant metastasis, advanced TNM stage, tumor relapse, and death(P<0.05). Increased expression of IMP3, tumors of the submandibular gland, and lymph node metastasis were independent prognostic factors of disease-free survival(DFS). In addition, IMP3 was a strong predictor of overall survival(OS) together with distant metastasis and intermediate and high-grade tumors.Conclusions: IMP3 expression is highly important in evaluating the outcome of MEC. IMP3 can be used to differentiate MEC from PA of salivary glands. Objective: Mucoepidermoid carcinoma (MEC) is the most common primary malignancy of the salivary glands. Insulin-like growth factor-II m RNA-binding protein-3 (IMP3) is an important prognostic factor in some cancers and a tool that differentiates between benign and malignant pancreatic lesions. This study aimed to identify a relationship between the expression of IMP3 and the outcome of salivary gland MEC, as well as to differentiate MEC from pleomorphic adenoma (PA). Methods: Tissue specimens from 70 cases of salivary gland MEC, 40 cases of PA, and 10 cases with normal salivary gland were examined immunohistochemically for IMP3. The association among the expression of IMP3, clinicopathological characteristics and patient’s survival was. Results: IMP3 was present in 51.4% of MEC but absent in PA and normal salivary gland tissues. IMP3 expression was associated with age> 60 years, submandibular gland tumors, tumor size> 4 cm, high-grade tumors, lymph node metastasis, involvement of Surgical margins, perineural invasion, distant metastasis, advanced TNM stage, tumor relapse, and death (P <0.05). Increased expression of IMP3, tumors of the submandibular gland, and lymph node metastasis were independent prognostic factors of disease-free survival ). IMP3 was a strong predictor of overall survival (OS) together with distant metastasis and intermediate and high-grade tumors. Conclusions: IMP3 expression is highly important in evaluating the outcome of MEC. IMP3 can be used to differentiate MEC from PA of salivary glands.