The reports of transfer of the medial arm flap have been inconsistent, and confusion remains about its anatomy and use. In 40 fresh cadaver arms, the vascular supply to the medial side of the arm was studied after latex injection. The superior ulnar collateral artery was present in 39 of 40 dissections and was the most consistent prominent blood supply to this area. In 57.5% of dissections, direct cutaneous arteries < 1.0 mm were present, and in 47.5%, multiple muscular cutaneous arteries < 1.0 mm were present. Although the blood supply to the medial arm flap is multiple, at least one pedicle < 1.0 mm can be found in all dissections. To date, 10 consecutive medial arm flaps were used to cover upper and lower extremity defects without any flap loss. With knowledge of the anatomical variations, the medial arm flap is a plausible reconstructive option.