n reconstructive surgery, microvascular free tissue transfers have gradually evolved from being a procedure of last resort to becoming a first choice operation in the last two decades. For this reason, careful preoperative assessment of the vascular anatomy of both donor tissue pedicles and recipient vessels is mandatory when planning these reconstructive procedures, and CDI has proved to be very useful for this purpose. Many other CDI applications in reconstructive microsurgery have been introduced recently, 1 and its contribution in assessing the vascular morbidity of the radial forearm flap is presented in this paper. Use of the radial forearm flap, a fasciocutaneous flap supplied by the radial artery, is a versatile and reliable technique for different reconstructive problems. The aim of the present study is to assess the changes in flow patterns of forearm arteries caused by excision of the radial artery when harvesting the radial forearm flap to clarify the vascular morbidity. To this purpose, a prospective study was designed using CDI for preoperative and postoperative quantitative flow measurements in forearm arteries. The aim of the present study was to assess the changes in flow patterns of forearm arteries produced by excision of the radial artery when harvesting the radial forearm flap. A prospective study using color duplex imaging for quantitative flow measurements was accomplished in 11 patients. After raising the radial flap, the forearm flow tended to increase overall, the ulnar (P = 0.04), the posterior interosseous (P = 0.003), and the anterior interosseous (P = 0.003) arteries being responsible for this tendency. Therefore, harvesting of a radial flap must not be considered as causing vascular morbidity in terms of blood supply to the hand. KEY