The hemodynamic effects of captopril (CPT) alone and in combination with the beta-adrenergic receptor agonist terbutaline (TBT) were evaluated in 10 patients with severe chronic congestive heart failure (CHF). The heart rate remained unchanged, while CPT lowered mean systemic blood pressure from 86 to 64 mm Hg (p less than 0.001) and decreased left ventricular filling pressure markedly from 27 to 19 mm Hg (p less than 0.001). The addition of TBT produced no further change in these variables (p greater than 0.05). Simultaneously, CPT augmented cardiac index (CI) from 2.1 to 2.9 L/min/m2 (p less than 0.001) and stroke index (SI) from 27 to 37 ml/beat/m2 (p less than 0.001). Concomitant CPT-TBT further raised CI to 3.2 L/min/m2 and SI to 40 ml/beat/m2 (both less than 0.001). Further, the CPT-effected decline in total systemic vascular resistance from 1577 to 841 dynes . sec . cm-5 (p less than 0.001) was not reduced additionally by CPT-TBT combination (p greater than 0.05). These results indicate than both CPT and TBT markedly augment cardiac function in CHF. Moreover, the salutary effects of the systemic vasodilator appear additive to the beneficial actions of the beta-adrenergic receptor agonist, thereby providing substantial augmentation of the function of the failing heart.