The regulation of the peripheral-limb circulation was investigated in 21 patients suffering from chronic cardiac failure (NYHA stage II and III). In 11 patients the extremital circulation was intact, while 10 patients suffered from peripheral obliterative arterial disease, too (intermittent claudication or rest pain). The control group consisted of 75 subjects with normal cardiac condition. In 35 of the control subjects the peripheral circulation was intact, the remaining 40 suffered from extremital venous isotope dilution technique. In congestive heart failure the limb blood flow and the limb oxygen consumption slightly diminished, but remained in the normal range. The limb vascular resistance significantly increased. In patients suffering from intermittent claudication or rest pain, the marked diminution of the limb blood flow and elevation of the vascular resistance was more pronounced in congestive heart failure than in healthy subjects. The pathologically elevated limb vascular resistance decreased and the limb blood flow significantly increased in congestive heart failure on administration of vasodilator drugs. A pathological and mostly reversible increase in extremital vascular resistance is the most characteristic sign of the peripheral circulation in congestive heart failure.