Occlusive arterial disease as a form of presentation of homocystinuria. Homocystinuria was first described in 1962. The disease affects several systems including the eyes, skeletal and nervous and vascular systems. We present the case of a 28-year old woman who presented with a severe occlusive arteriopathy. Screening for the most usual causes of arterial disease in young patients was negative, but a study of aminoaciduria and column chromatography confirmed the diagnosis of B6-responsive homocystinuria. Although it was necessary to amputate her left leg, the patient remains asymptomatic 16 months after B6 therapy was started. 