Peripheral arterial occlusive disease (PAOD) results from atherosclerosis of large and medium peripheral arteries, as well as the aorta, and has many risk factors, including smoking, diabetes, hypertension, and hyperlipidemia. PAOD often coexists with coronary artery disease and cerebrovascular disease. Cross-matching a population-based list of Icelandic patients with PAOD who had undergone angiography and/or revascularization procedures with a genealogy database of the entire Icelandic nation defined 116 extended families containing 272 patients. A genomewide scan with microsatellite markers revealed significant linkage to chromosome 1p31 with an allele-sharing LOD score of 3.93 (P=1.04 x 10(-5)). We designate this locus as "PAOD1." Subtracting 35 patients with a history of stroke increased the LOD score to 4.93. This suggests that, although PAOD and other vascular diseases share risk factors, genetic factors specific to subtypes of vascular disease may exist.