It is possible for a proximal arterial source to lead to distal atheroembolism even in the presence of chronic occlusive disease. However, no monitoring technique has been established regarding detection of peripheral emboli through the collateral circulation in the lower limbs. We report a 60-year-old woman and a 73-year-old man with iliac stenosis and complete occlusion of the ipsilateral superficial femoral artery in whom Doppler ultrasound successfully detected microembolic signals (MES) at the tibioperoneal trunk during percutaneous transluminal angioplasty (PTA) and stent placement. By means of continuous Doppler ultrasound monitoring, 29 MES were successfully detected immediately after PTA or stent placement (MESp) and 64 MES were detected immediately after the contrast medium administration (MESc). MESc generated significantly higher intensities (median 28, range 7 to 38) as opposed to MESp (median 21, range 5 to 35, p = 0.017). In addition, the intensity of MES after prestent PTA (n = 8, 25 dB, 12-35 dB) and stenting (n = 18, 22 dB, 9-35 dB) was significantly higher than that of MES after poststent PTA (n = 3, 13 dB, range; 5-16 dB), respectively (p = 0.041, p = 0.034). Iliac PTA and stent placement were successful. Ankle/brachial pressure index and the symptoms improved in both patients, who showed no embolic symptoms after the procedure. This study suggested that it was possible to detect peripheral microemboli through the collateral circulation by Doppler ultrasound monitoring and that this technique would be helpful to investigate the mechanism of embolization in patients with PTA and stent placement.