A simple one minute exercise test was used as a screening test for asymptomatic peripheral arterial disease in a sample of 100 men in their sixth decade with no previous referrals for cardiovascular disease. Other investigations included resting ECG, non-invasive carotid artery assessment, and plasma biochemical analysis. Of these 100 men (mean age 56), 10 had evidence of peripheral disease on exercise testing, four had ischaemic changes on resting ECG, and one showed evidence of carotid artery stenosis. A total therefore of 15 out of 100 (15%) had asymptomatic arterial disease. These 15 men had increased concentrations of plasma fibrinogen (4.3(0.7) g.litre-1) compared with men with no evidence of arterial disease (3.5(0.7) g.litre-1; p less than 0.01). The one minute exercise test is a useful screening test for peripheral arterial disease, and this pilot study suggests that raised plasma fibrinogen concentrations may be an important risk factor.