Pentoxifylline is approved by the Food and Drug Administration for the treatment of patients with intermittent claudication on the basis of chronic occlusive arterial disease of the limbs. It is not a substitute for surgical bypass or removal of arterial obstructions, but will improve function and symptoms of the disease state. The mechanism by which pentoxifylline works is not well known, but appears to be related to erythrocyte adenosine triphosphate (ATP) concentrations and the phosphorylation of erythrocyte membrane proteins, both mechanisms resulting in an improvement in erythrocyte flexibility. Efficacy studies indicate that pentoxifylline is significantly more effective than placebo or nylidrin therapy. Adverse reactions are mainly of the gastrointestinal type and are minimized by the use of a controlled-release dosage form.