Percutaneous transluminal angioplasty (PTA) for severe arteriosclerotic stenosis in the cervical internal carotid artery (ICA) was successfully carried out in 23 cases between December 1994 and August 1996. In order to analyze the condition of the cervical ICA in the early stage after PTA, 12 stenotic lesions of 11 cases were exposed to follow-up study of stenotic cervical ICA after PTA with magnetic resonance angiography (MRA) 1 to 150 days postoperatively. In six lesions, the diameter of the cervical ICA was dilated sequentially. In another four lesions, the diameter of the cervical ICA was decreased in the first three weeks and dilated over the next three weeks. Angiographically, these lesions had a small intimal flap at the balloon dilated portion, which was speculated to cause the turbulent flow in the first stage. In the remaining 2 lesions, restenotic changes in cervical ICAs were observed within three weeks after PTA. Follow-up angiography was performed over three months after PTA in five cases of this series and compared with MRA. Consequently, the diameters of the cervical ICA between angiography and MRA were closely correlated. The evaluation of the lesion after PTA of the cervical ICA demonstrated that MRA is beneficial, but within three weeks after PTA, caution should be paid for underestimation of the small intimal flap on MRA.