Arteriovenous malformation is a vascular anomaly due to the hamartomatous proliferation of the subpapillary vascular plexus which exhibits multiple arteriovenus shunts. Various tumors can be developed in the port-wine stain, such as, pyogenic granuloma, basal cell carcinoma, squamous cell carcinoma, tufted angioma, giant proliferative hemangioma, and lymphangioma circumscriptum. We report a case of arteriovenous malformation arising in the port-wine stain. The pathogenesis of development of arteriovenous malformation in the port-wine stain is still unknown, but may be related to localized exaggerations of ectasia.