Introduction: Analysis of selected MRI parameters in initial MRI for the characterization of ovarian masses enables differentiation between mucinous ovarian carcinoma and metastatic ovarian tumors. Material and Methods: A prospective analysis of contrast-enhanced MRI of patients with suspected ovarian masses diagnosed in ultrasound and CT examination. Morphological criteria, such as the size of lesion, bilateral location, presence of “mille-feuille sign”, so-called Seidman criteria, as well as the diffusion weighted imaging and dynamic contrast enhancement of each lesion, were evaluated. Patients were allocated into two groups; the first group contained patients with mucinous ovarian cancer, and the second group contained patients with metastatic ovarian tumors. Results: A total of 35 patients were enrolled into the study. Median age was 49 in the first group and 59 in the second group of patients (p = 0.04). In the first group, all patients (100%) had unilateral lesions, and in the second group, 94% had bilateral tumors (p < 0.000001). In the first group, a tumor size equal or greater than 10 cm was present in 80% of patients, and the same was true for 21% of patients in the second group. The mille-feuille sign was present in 30% of patients from the first group and in 64% of patients from the second group. In the first group of patients, TTP was 410 and Perf.Max Enhancement was 141; in the second group, they were, respectively, 154 and 167 (p = 0.0001 and p = 0.5). Median ADC values in the first group were significantly higher in the first group than in the second group (p < 0.01). Conclusions: Significant differences in TTP and ADC values as well as in Seidman criteria enable reliable differentiation between the analyzed groups of tumors.