To evaluate assessment of tumor regression with magnetic resonance (MR) imaging, the authors studied 21 consecutive patients with cervical carcinoma tumors that were more than 3 cm in diameter. Thirteen of the 21 also demonstrated parametrial invasion. In all cases, MR imaging was performed both before and after chemotherapy. Pathologic specimens were obtained at hysterectomy in all patients. Comparison of pathologic and MR imaging findings after chemotherapy showed that all tumors decreased in size. Size of tumor was correctly determined at MR in 17 cases and was slightly overestimated in four cases. Five patients had residual parametrial invasion that was histologically confirmed. In detecting parametrial spread after treatment, MR imaging had an accuracy of 90.4%. Tumors had high signal intensity on T2-weighted images, whereas intratumoral necrosis was characterized by low signal intensity on the same images. Peritumoral inflammatory tissue found at pathologic examination in four of 21 cases was not specifically identified on MR images. In patients with invasive cervical carcinoma, MR imaging may be useful in evaluating tumor response to preoperative chemotherapy.