A functional evaluation was made of osteocutaneous radial forearm flap donor upper extremities at a mean 19.4 months postoperatively. Donor deficits were evaluated as follows: (1) skin: subjective appearance and durability; (2) skeleton: range of motion of adjacent joints; (3) vessels: cold intolerance, digital temperature, digital-brachial index; (4) muscle: key pinch; (5) nerve: two-point discrimination of dorsal first web space. Ten consecutive patients with a mean donor site area of 51.5 cm2 and mean length of harvested radius of 10.9 cm were studied. Incomplete skin graft take at the donor site (7 of 10 patients) and appearance of fair or poor (6 of 10 patients) were frequent cutaneous complications. Wrist range of motion was decreased with pronation (90%), flexion (90%), and extension (89%). Mean digital temperature, comparing extremities that did (operated) and did not (nonoperated) undergo surgery, or comparing the radial artery–supplied fingers to the ulnar artery–supplied fingers within the same operated hand showed no effect from the lost radial artery. Mean digital–brachial index was 1.24 for the nonoperated and 1.15 for the operated extremity. Key pinch on the operated side was a mean of 74% of the nonoperated side. Although raising the flap creates multiple tissue deficits, each with the potential to alter upper extremity function, detailed functional evaluation failed to demonstrate significant alteration in upper extremity function after flap harvest.