PURPOSE: To report three cases of sclerosing Wegener's granulomatosis in the orbit and to compare the histopathological morphology with those of other types of sclerosing orbital inflammation. METHODS: We analysed the clinical data along with histopathological specimens from orbital biopsies and from two enucleated eyes. RESULTS: All three patients had longstanding inflammation in the orbit and involvement of the paranasal sinuses. Proptosis, impaired ocular motility and reduced visual acuity dominated the clinical picture. All histopathological specimens featured granulomatous inflammation, tissue necrosis, vasculitis and widespread dense fibrosis. In certain areas of all specimens the fibrous tissue was arranged in characteristic concentric, onionskin-like whorls of collagen around obliterated small blood vessels. CONCLUSIONS: Wegener's granulomatosis may lead to orbital fibrosis and sclerosis. The stromal changes and cellular infiltrate resemble the non-specific orbital inflammation previously termed orbital pseudotumour. We present the first 'onionskin' lesions in association with Wegener's granulomatosis in the orbit. This latter morphology may represent an abnormal fibrotic reaction in inflammatory tissue.