In the patients with invasive cervical carcinoma, the accurate assessment of parametrial invasion greatly affects the therapeutic choice between surgery and radiation therapy. As a matter of fact, surgery is usually performed only in the patients with carcinoma confined to the cervix, whereas those with parametrial involvement, or more advanced stages, are treated with radiation therapy. This prospective study was aimed at investigating the comparative adequacy of CT and MR imaging in assessing parametrial status in the patients with invasive cervical cancer. Twenty-one consecutive patients, with histologic diagnosis of cervical carcinoma, were investigated. All of them were clinically considered as having invasive cervical cancer (FIGO stages IB-IIB), and subsequently underwent surgery. In all cases, detailed histology of the parametrium was obtained. Pathologic data were compared with CT and MR findings in all cases. As for assessing parametrial involvement by cancer, CT had 62% accuracy, 63% sensitivity, and 60% specificity, versus MR imaging 81% accuracy, 69% sensitivity, and 80% specificity. Therefore, MR imaging appears to be superior to CT in assessing the parametrial status of patients with invasive cervical carcinoma; the method yields valuable information for treatment planning.