To investigate blood flow alterations and their determinants after free flap transfer, we focused on a vascularized latissimus dorsi muscle segment for reconstruction of the paralyzed face as an ideal model, since the vascular pedicle and type of flap are identical among patients. Seventeen patients were studied using color Doppler ultrasonography at 6 time points from before the operation to >1 month postoperatively. The influences of preoperative facial arterial flow volume, volume of muscle, and duration of ischemia on postoperative pedicle arterial flow were analyzed. Arterial flow volume decreased dramatically after revascularization and remained constantly low in comparison with preoperative blood flow volume. The shape of the blood velocity waveform reflecting downstream vascular impedance changed, but recovered to the baseline state within 6 days. Preoperative flow volume and transferred muscle weight correlate with postoperative flow volume for 6 days postoperatively. The duration of ischemia was not influential.