The clinical usefulness of tissue reflection spectrophotometry in the prognosis of ischemic limbs was evaluated. The diseased group (n=12) consisted of 7 cases of femoral artery thrombosis, 4 cases of chronic obstructive arteriosclerosis and 1 case of femoral vein thrombosis. The normal control group consisted of 14 limbs in 7 normal subjects (n=14). Index of tissue hemoglobin concentration (IHb) was 37.3±4.5 (n=14) in the normal control group and 38.5±16.9 (n=12) in the diseased group, which was not significantly different. In a subgroup of patients who required amputation or developed necrosis (severe subgroup), the value was 54.2±1.7 (n=6). This was significantly higher than the value of 22.8±8.5 (n=6) obtained in a subgroup of patients who received the conservative treatment of thrombectomy (mild subgroup) (p<0.05). Index of tissue oxygen saturation (ISO₂) was 28.0±4.9 (n=14) in the normal control group, and 9.1±2.7 (n=12) in the diseased group (p<0.05). 1502 was 7.0±1.6 (n=6) in the severe subgroup which was significantly lower than 11.2±1.9 (n=6) in the mild subgroup (p<0.05). Tissue reflection spectrophotometry therefore appears to provide clinically useful information for the prognosis of ischemic limbs.