Ergot's derivatives are widely used in the treatment of migraine and in the prophylaxy of deep venous thrombosis in association with heparin. Clinical ergotism is rarely observed and can affect all the arteries, especially of the inferior limbs. Vasospasm of the peripheral arteries and collateral formation are specific findings on angiography. We report the illustrative case of a 38 years old woman hospitalized for a small bowel occlusion. She suffers from chronic migraine treated by ergotamine tartrate. During her hospitalization, she develops an acute ischemia of the lower limbs. An ergotism was clinically suspected and confirmed by Duplex sonography which demonstrate multiple vasospasm. Under iv sodium nitroprusside and peridural analgesia the spasm resolved in 24 hours. The control Duplex sonography confirm the normality of the lower limb arteries. This examination modality allow a non-invasive diagnosis and evolution control of arteriospasm.