A right proximal external carotid to distal middle cerebral artery bypass with a prosthetic tube graft was performed in a patient with intermittent cerebral ischemia due to middle cerebral artery stenosis. The patient was relieved of his symptoms, and he was neurologically normal 3 months after operation. Angiography 3 months postoperatively revealed flow through the graft and excellent filling of the middle cerebral circulation, both retrograde and antegrade. Early results suggest that an expanded polytetrafluoroethylene graft may be useful as a vascular conduit if suitable autogenous vessels are unavailable or have failed.