Ultrasonography is a new imaging method for visualizing peripheral nerves. In vasculitic neuropathy, pain or axonopathy often can prevent the lesion from being localized during electrophysiological examinations, but the ability of ultrasonography to evaluate it morphologically is unknown. Our aim was to determine whether ultrasonography could be used to detect abnormalities in tibial vasculitic neuropathy at the medial ankle. We evaluated 11 tibial nerves in 8 patients with tibial vasculitic neuropathy, and 35 tibial nerves in 35 control subjects. In the controls, the tibial nerve was successfully visualized as a hyperechoic nodule with multiple round hypoechoic areas transversely; in the patients, the tibial nerve appeared enlarged and hypoechoic. The affected nerve area was significantly larger (13.5 +/- 3.7 mm(2)) than in controls (7.2 +/- 1.5 mm(2)). Our results suggest that ultrasonography is a useful neuroimaging method for evaluation of tibial vasculitic neuropathy, especially when nerve conduction study findings are inconclusive.