PURPOSE: To evaluate the MR findings of extra-abdominal fibromatosis and the role of MRI in primary diagnosis MATERIALS AND METHODS: Fifteen cases in of histologically proven extra-abdominal fibromatosis in 13 patients were retrospectively reviewed. T1-weighted and T2-weighted images were obtained in axial, coronal and sagittal planes. Gd-enhancement was performed in 14 cases, and dynamic enhancement studies in two. All lesions were evaluated for mass shape and margin definition. RESULTS: Among the 15 cases, tumors of the buttock accounted for five, and tumor of the thigh for two. In eight cases tumors were intermuscular and in six cases were intramuscular. In ten cases (67 %) the mass extended along the long axis of the body and in 14 of 15 cases (93%) focal infiltration of adjacent structures was visible. The signal intensity of the lesion was in all cases inhomogeneous on both T1 and T2 weighted images. As seen on Gd-DTPA enhanced scans, the masses were inhomogeneously enhanced. In all cases MRI revealed star-shaped linear strands or a band-like low signal area in the mass. These features were not enhanced and were arranged along the long axis of the mass. CONCLUSION: MR findings of extra-abdominal fibromatosis were relatively characteristic and helpful for primary diagnosis of the condition.