In small vessel vasculitides, imaging studies aid in determining disease extent and activity, localization for biopsy, and for disease monitoring. They do not directly delineate the vasculitic lesion. Imaging studies focus on the upper and lower respiratory tract. Cranial magnetic resonance imaging (MRI) shows upper respiratory and retrobulbar granuloma in Wegener's granulomatosis. Furthermore, MRI depicts both mastoiditis and mucosal inflammation of the ear, nose, and throat. It is sensitive but not specific for the detection of cerebral vasculitis. Computed tomography (CT) reliably detects osseous facial lesions. Chest radiography in two planes remains the standard method of investigation for the lower respiratory tract. High-resolution CT aids in detecting further interstitial pathologies. Medium-sized vasculitides frequently occur with aneurysms. The classification criteria for polyarteritis nodosa involve the angiographic detection of visceral aneurysms. Patients with Kawasaki disease may develop coronary aneurysms that may be described by echocardiography or angiography according to diagnostic criteria. In large-vessel vasculitides such as temporal arteritis (giant cell arteritis) and Takayasu arteritis, MRI, MR-angiography, CT, CT-angiography, and duplex sonography delineate characteristic homogenous wall thickening with or without stenoses in the aorta and other arteries. There is a high correlation with angiography and positron emission tomography. Duplex sonography of the temporal arteries has a high sensitivity and specificity for the diagnosis. Data on temporal artery MRI in giant cell arteritis have recently been published.