Cardiodynamic studies using a non-invasive computerised thoracic electrical bioimpedance (TEB) equipment were performed in 35 patients presenting with acute lower limb ischaemia of presumed embolic origin, and in 36 age-matched control patients without emboli. Patients who presented with imminent gangrene were promptly operated upon, whereas those who had less severe ischaemia were treated initially with heparin only. In the former group, cardiac output and myocardial contractility were very low on admission, while systemic vascular resistance was high. Cardiac output was further decreased when measured immediately after revascularisation, whereas it had become normal 2 days later. In patients with less severe acute ischaemia, cardiac output and myocardial contractility values on admission were similar to those of control patients, and no changes were observed after 2 days of conservative treatment. Overall, cardiac output on admission was significantly related to the simultaneously observed severity of the limb ischaemia. A low cardiac output (less than 1.7 l/min m2) on admission was found to predict severe cardiac complications (60% mortality within 10 days), whereas clinical assessment of cardiac failure on admission was poorly related to outcome. We conclude that patients with acute lower limb ischaemia of presumed embolic origin often have unrecognised poor cardiac function, which is related to the severity of the limb ischaemia and to outcome. By routine non-invasive TEB cardiodynamic measurements, high risk patients can rapidly be identified and proper treatment regimes be instituted in each individual patient.