MRI of the head was performed in 25 patients suffering from Wegener's granuloma. 23 patients showed evidence of mucosal thickening in the paranasal sinuses, the middle and inner ears and in the mastoid cells; these were characterised by low signal intensity of T1-weighted and high signal intensity of T2-weighted images. In 10 patients there were granulomas in the paranasal sinuses and in the orbits which showed low signal intensity of both T1-weighted and T2-weighted images. In 4 patients, additional images were obtained after the intravenous injection of Gd-DTPA. In 2 patients this resulted in non-homogeneous contrast accumulation in the granuloma. In 7 patients there were signal changes in the brain which were typical of infarcts. The complete extent of bone destruction in the facial skeleton was visible only by CT.