To evaluate the value of sagittal diffusion weighted imaging (sag DWI) in the staging of endometrial cancer (EC), and to analyze the difference of apparent diffusion coefficient (ADC) between different stages and pathological grades of EC.EC is a common malignant tumor of the female genital tract, the standard of staging is surgical pathology staging, which based on the depth of the invasion of the muscular layer, the involvement of the cervical stroma, whether has local diffusion and the existence of lymph node or distant metastasis. The prognosis and treatment of different stages of EC were not the same. At the same time, the depth of the pathological grade of EC and the depth of the muscular layer were closely related to the lymph node metastasis rate and the overall survival rate of the patients. For a long time, MR has been considered as the most accurate imaging technique for evaluating EC. It has been reported that DWI has a high accuracy in the evaluation of the depth of EC, and ADC can predict the pathological grade of EC. Because of the position of the uterus is forward, precursor, or posterior oblique, sagittal MR images can more accurately display the whole uterus.The MR data of 29 cases with EC were retrospectively analyzed, and cases were confirmed by operation and pathology. Refer to the 2009 FIGO staging criteria, the preoperative staging of EC was performed with sag T2WI and sag DWI. Standard for surgical pathology staging, the accuracy of EC staging by sag T2WI and sag DWI were evaluated and compared respectively. The ADC values of EC were measured by two observers, the data consistency of two observers were measured by the intra-class correlation coefficients (ICC), the difference among different stages and pathological grades were compared with Mann-Whitney U test.Standard of surgical pathology, the accuracy of sag T2WI in the diagnosis of EC in stage Ia, Ib, II, III were 87.5%, 50%, 100%, 33.33%, respectively. The accuracy of sag DWI in the diagnosis of EC in stage Ia, Ib, II, III were 87.5%, 83.33%, 100%, 33.33%, respectively. The accuracy of sag DWI in the diagnosis of stage Ib of EC was higher than that of sag T2WI, but had no statistically significant difference (P=0.273), the accuracy of stage Ia, II and III were equal to sag T2WI. The consistency of the data obtained by the two observers was good (ICC=0.930). The average ADC values of stage Ia, Ib, II and III were (1.00±0.1)×10-3mm2/s, (0.90±0.24)×10-3mm2/s, (0.80±0.10)×10-3mm2/s and (0.80±0.11)×10-3mm2/s, respectively. The difference between stage Ia and II, stage Ia and III had statistically significant difference (P ＜0.05) . The average ADC values of grade G1, G2 and G3 were (1.00±0.14)×10-3mm2/s, (0.90±0.08)×10-3mm2/s, (0.70±0.10)×10-3mm2/s, respectively, the difference all had statistically significant (P＜0.05).The preoperative staging of sag DWI with EC was similar to sag T2WI. ADC value can be used to identify different pathological grades and some different stages of EC, with the increase of the pathological grade the ADC value decreased.