Retroperitoneal fibrosis has been reported in several patients with Wegener granulomatosis (WG), but only three isolated cases of dorsal prevertebral lesions, closely resembling fibrosing mediastinitis, have been published so far. We describe four new WG patients (two men, two women), 49–59years old at diagnosis, with dorsal prevertebral lesions, mainly right-sided, and with adjacent pleural thickening in two. These lesions were detected on computed-tomography scans at diagnosis in two patients, and occurred later in the two others. Only one of them had mild back pain. Two patients’ lesions were biopsied, revealing granulomatous inflammation. In one patient, the lesion regressed under WG treatment. Lesion size did not change in the remainings. Intralesional calcifications appeared in two. None of the patients had local bone erosion, vascular or neurological complications. These prevertebral lesions might represent a dorsal form of retroperitoneal fibrosis in WG, but usually with a more benign presentation and course. WG should be included in the differential diagnosis of fibrosing mediastinitis (with tuberculosis, neoplastic diseases, sarcoidosis, histiocytosis and inflammatory pseudotumor), which may have a similar radiological appearance.