A focused history and thorough physical examination, combined with a working knowledge of the normal vascular anatomy, can help identify most vascular abnormalities of the upper extremity. Technologic improvements now allow accurate diagnosis by noninvasive methods. Most abnormalities can be categorized into one of five major diagnostic groups: traumatic, compressive, occlusive, tumoral (malformation), and vasospastic. Behavioral modifications and pharmacologic agents may improve symptoms. Appropriately selected surgical candidates often experience pain relief and functional improvement.