Eighteen patients developed vascular complications of drug abuse. Nine cases involved the upper extremities; seven, the lower extremities. Treatment consisted of heparin anticoagulation and the intra-arterial injection of vasodilator drugs. All the upper extremity cases recovered. Five of the seven lower extremity cases required surgical treatment; three required amputation. In the two other patients, systemic vascular complications developed. One of these consisted of aneurysms of the mesenteric and splenic arteries and the other, Candida endocarditis with peripheral embolism. The former responded to extensive medical treatment and the latter to aortic valve replacement.