In terms of reconstructive surgery, the upper extremity is perhaps one of the most challenging regions compared to other body regions, because preserving and restoring function in this region is of great importance compared to other body regions. Injuries to the hand and upper extremity can occur for many reasons and with different mechanisms, and each patient’s injury may require very different reconstructive procedures. With the development of microsurgery, the use of free flaps is increasing in order to achieve optimal results in upper extremity reconstruction. In order to achieve more optimal results in the upper extremity, the reconstructive elevator option has been applied more frequently in many centers instead of the reconstructive ladder option. In this chapter, free flaps used in upper extremity reconstruction will be evaluated in three separate sections. In the first part, free flaps commonly used in the upper extremity will be evaluated on the basis of anatomical regions. In the second part, the reconstruction of the upper extremity with various free bone flaps, which are becoming increasingly popular, will be evaluated separately. In the third part, free functional muscle transfers, which have been widely studied in recent years, will be evaluated. In this section, the most commonly used free flaps in upper extremity reconstruction will be discussed. Reconstruction operations are patient based and one or more of these flaps can be used together or in separate sessions. Again, the choice of the flap may vary depending on the experience of the surgeon and the center.