A clinical study was carried out in 31 patients (39 limbs) with thromboangiitis obliterans (TAO, Buerger's Disease) by Chinese herbs "Vascular No.3". Doppler ultrasound flow velocity tracing at the femoral, popliteal, posterior tibial and dorsalis pedis levels and blood pressure at the ankle level were measured. The results showed that TAO patients treated with "Vascular No.3" had a total effective rate of 92.3% and a distinct improvement of 76.9%. The results of Doppler ultrasound proved that "Vascular No.3" significantly decreased arterial lumen stenosis level, increased blood velocity and local flow, promoted developing arterial collaterals and improved vaso-functional conditions.