Two-hundred and three MR examinations were reviewed of 177 patients with lipomatous, fibrous and muscular tissues tumors which were evaluated at staging or during the follow-up. All examinations were obtained with a 1.5T superconductive magnet, and both T1 and T2-weighted images were acquired. Its high-contrast resolution, its direct multiplanarity and its allowing both T1 and T2-weighted images to be obtained, are the most important characteristics of MR imaging. In our experience, MRI demonstrated a high overall accuracy (96.1%)-95.2% at restaging alone--with similar sensitivity both at the staging of the disease (100%) and during the follow-up (97%). Overall sensibility was 97.6%. MR specificity in histologically proven relapses was 87.9%. Even though it is gradually assessing itself as the most important method in the evaluation of soft tissues masses, MRI allows an histological diagnosis to be made only in lipomatous tumors and in benign fibrous tumors, due to their specific signal features. The commonest though aspecific finding is a soft tissue mass with relatively low signal intensity in T1 and high signal intensity in T2-weighted images. In our opinion, MR imaging is the method of choice during the follow-up of the disease, whereas it is probably a complementary technique in the staging.