Obstetric brachial plexus palsy ( OBPP ) can be subdivided into two distinct phases: initial (or infant) and late (or child ) phase of OBPP. In the late phase of OBPP, there are three types of residual deformities : ( 1 ) motor recovery with aberrant reinnervation, ( 2 ) motor recover with paralysis (complete atrophy), or paresis ( incomplete ), and ( 3 ) motor recovery following primary nerve reconstruction. Traditional tendon or muscle transfer techniques do not provide satisfactory reconstruction for those deformities. Many of these patients require more complex techniques such as functioning free muscle transplantation (FFMT). Between July 1997 and July 2002 ( a 5-year period ) 59 late phase of OBPPs were reconstructed with 65 FFMTs at Chang Gung Memorial Hospital by the same surgeon ( DCC Chuang ). Six patients had two FFMTs for reconstruction of the different deficits. The function restored by the FFMT included elbow flexion ( 35 FFMTs ), elbow extension ( 2 FFMTs ), finger extension (7 FFMTs ), finger flexion (8 FFMTs), finger extension plus elbow flexion by using one muscle ( 13 FFMTs ). The donor transferred nerve used as the muscle neurotizer included spinal accessory nerve, intercostal nerves, musculocutaneous nerve, or contralateral C7 spinal nerve. Guidelines by using FFMT for different deficits in the late phase of OBPP are provided regarding the indications, methods, results and optimum timing of FFMT.