The aim of our study was to evaluate the diagnostic performance of magnetic resonance imaging (MRI) in the pretreatment evaluation of myometrium invasion in endometrial cancer. Our retrospective study concerns 89 patients with endometrial cancer, who had preoperative MR evaluation of myometrium invasion and we compared it with histological results. Considering histological type and grade, we had excluded patients with poor prognosis, and separately evaluated those cases where the depth of myometrium invasion is the main prognostic factor determining the choice treatment. Of the 89 cases MRI had accurately evaluated the depth of myometrial invasion in 75 patients. Based on data from all cases, we found the sensitivity of detection of deep myometrial infiltration by MRI (Sv) 71 %, specificity (Sp) 92 %, accuracy (Acc) 84 %, positive predictive value (PPV) 86 % and negative predictive value (NPV) 83 %. Excluding patients with poor prognosis according to histology and grade, these data were Sv 71 %, Sp 95 %, Acc 87 %, PPV 90 %, NPV 84 %. In conclusion, MRI is an efficient diagnostic tool in assessing myometrial infiltration, which is necessary for proper preoperative staging and therapy planning, including evaluation of the necessity of lymphadenectomy. Certain factors may interfere with evaluation of MRI results, thus hindering the precise determination of the level of myometrial infiltration.