Quantitative data concerning the effect of arterial compliance (AC) on the effectiveness of intra-aortic balloon counterpulsation (IABC) are lacking. The main objective of this study was to investigate the relationship between AC and IABC performance. For this purpose we constructed a Windkessel, lumped-element, hydraulic model of the systemic circulation. The model consisted of a left ventricular assist device (LVAD), a compliance chamber, a peripheral resistor and two open reservoirs. Two Datascope Driving systems were used to operate the LVAD and intra-aortic balloon. We studied the effect of arterial compliance on the effectiveness of IABC at different levels of mean pressure (55, 75 and 95 mmHg) and heart rates (80, 100, 120 bpm). Three indices were used to evaluate IABC performance: the reduction of systolic and end-diastolic "arterial" pressure and the augmentation of diastolic pressure, induced by the IABC. A 22% decrease in AC (1.8-1.4 ml/mmHg) lead to a 30-40% increase in the indices of IABC performance, independently from pressure. In conclusion, arterial compliance significantly affects IABC efficacy and it could be considered as a further clinical criterion to decide IABC application.