In heart failure in man the role of wave generation by the ventricle and wave reflection by the vasculature is contentious. The aim of this study was to compare wave generation and reflection in normal subjects with patients with stable compensated heart failure. 29 normal subjects and 67 patients with heart failure (NYHA Class II or III) were studied by non-invasive techniques applied to the common carotid artery. Data were analysed by wave intensity analysis to determine the nature and direction of waves during the cardiac cycle. The energy carried by an early systolic forward compression wave (S wave) generated by the left ventricle and responsible for acceleration of flow in systole was significantly reduced in subjects with heart failure (p<0.001) and the timing of the peak of this wave was delayed. In contrast, reflection of this wave was increased in subjects with heart failure (p<0.001) but timing of reflections with respect to the S wave was unchanged. The energy of an expansion wave generated by the heart in protodiastole was unaffected by heart failure. Carotid artery wave speed and augmentation index did not differ significantly between subjects with heart failure compared with normal individuals. The ability of the left ventricle to generate a forward compression wave is markedly impaired in heart failure. Increased wave reflection serves to maintain systolic blood pressure but also places an additional load on cardiac function in heart failure.