Abstract： Objective:To investigate the differences in CT imaging features of head and neck mucoepidermoid carcinomas (MEC) from different origins and different histological grades.Methods:Clinical and CT imaging findings of 53 patients with pathologically proved MEC in the First Affiliated Hospital of Kunming Medical University admitted from January 2009 to May 2019 were retrospectively reviewed. On the basis of origins, all MECs were divided into 2 groups: large salivary gland group (23 cases) and small salivary gland group (30 cases). All MECs were further divided into 3 groups based on histological grades: highly differentiated (19 cases), moderately differentiated (28 cases) and poorly differentiated (6 cases). The CT imaging features of MEC from different origins and different histological grades (including location, number, size, morphology, boundary, density, calcification, cystic cavity, necrosis, bone changes, flat CT scan value, arterial phase CT enhancement value-added, venous phase CT enhancement value-added, enhancement method, adjacent structure invasion, cervical lymph node metastasis and distant metastasis) were analyzed and compared using t test, χ 2 test, Fisher exact probability or rank-sum test. Results:Comparisons of characteristics between different origins: only lesion size, morphology, bone changes, and plain CT values ( P<0.05) was significantly between different origin groups. There was no significant difference of residual image features ( P>0.05). Compared with MECs derived from large salivary glands, the small salivary gland group had larger MEC lesions, irregular shapes and was prone to have bone changes (including expansion and destruction). In addition, the plain scan CT value of MEC from the large salivary glands was slightly lower than that of the small salivary glands MEC (all P<0.05). Comparison of characteristics among different histological grade groups: only cystic cavity was statistically different (χ2=8.045, P=0.015). Compared with poorly differentiated MEC, highly differentiated MEC was more prone to have cysts (χ2=7.707, P=0.012). Conclusion:There are some differences in CT findings of head and neck MEC from different origins. The cystic cavity has reference value for evaluating histological grade.