OBJECTIVES: To investigate the Ankle/Brachial Pressure Index (ABI) for its suitability in daily practice to identify patients at atherothrombotic risk. To collect data on the prevalence of atherothrombotic events [coronary artery disease (CAD), stroke/transient ischaemic attack (TIA)], of 'hidden' (asymptomatic) versus 'known' (symptomatic) peripheral arterial disease (PAD) and treatment in the general practice population. DESIGN: Field survey from everyday Swiss practice. On five consecutive workdays, 276 doctors documented all patients, recording gender, age, history of atherothrombotic events, risk factors and family history. In the case of a previous stroke/TIA and/or CAD, or two or more risk factors were present at age >55, the ABI was determined. A total of 25,351 patients were included and 3921 ABI measurements were performed in eligible patients. SETTING: Practices of primary care doctors. PARTICIPANTS: All patients who visited one of the 276 participating doctors on one of five consecutive workdays were included in the survey. INTERVENTION: Data recording and measurement of the ABI on those patients who qualified. RESULTS: Of the patients 3.7% had symptomatic PAD. An additional 2.7% of hitherto asymptomatic patients were identified as being at high atherothrombotic risk by having an ABI value <0.9. Exactly 93.9% of the participating doctors considered the ABI measurement easy to incorporate into the diagnostic routine of patients presenting with risk factors. CONCLUSIONS: The ABI measurement is an easy-to-use, noninvasive and reliable means to identify patients at risk of atherothrombotic events. Identification of asymptomatic PAD leads to intensified targeted prophylactic atherothrombotic treatment that can reduce morbidity and mortality.