Vascular disorders constitute a civilisation threat, and they can affect the arterial, venous, and lymphatic vessels. Screening, diagnostics, reduction of modifiable risk factors, and appropriate treatment reduce the risk of progression and related complications, which are often associated with limb amputation and lead to disability.

The ankle-brachial index is a simple test for assessing the state of peripheral arteries. Its value also correlates with the risk of unwanted cardiovascular events. It plays an important role in the planning of compression therapy for patients with chronic venous insufficiency and is a useful prognostic tool for diabetics.

The aim of this paper is to discuss the theoretical basis for the ankle-brachial index measurement, its essence, and usefulness in the diagnosis of vascular disorders and factors that may affect its value.