The authors evaluated the efficacy of propionyl-l-carnitine, a drug able to reduce peripheral resistance and protect the cells against oxidative stress damage, in patients affected by peripheral arterial obliterative disease at class II of Fontaine. The study was performed on 22 patients according to a double-blind, randomized design in parallel with placebo. The drug was administered at a dosage of 1 g three times a day orally for 90 days. At recruitment and at the end of the study all patients underwent physical examination, treadmill test, doppler C.W. of the lower limbs, ankle/brachial index, dosage of tissue plasminogen activator (t-PA), plasminogen activator inhibitor-1 (PAI-1), hematocrit, hematic filtration, and viscosity. In the group treated with propionyl-l-carnitine a statistically significant increase of claudication distance, blood flow velocity, PAI-1 activity and red blood cell deformity was observed. These data suggest the usefulness of propionyl-l-carnitine in the treatment of patients affected by peripheral arterial obliterative disease.