Conclusions: Thoracodorsal nerve division or preservation does not significantly affect muscle contraction activity of the latissimus dorsi flap and distortion of the breast when latissimus dorsi muscle humeral insertion is also detached. Therefore, both cutting and saving the nerve are justified in latissimus dorsi flap breast reconstruction depending on whether the humeral insertion of the muscle is preserved intact or divided and the flap islanded. The study shows that there is no tangible benefit in dividing the nerve when the flap is islanded. (c) 2014 British Association of Plastic, Reconstructive and Aesthetic Surgeons. Published by Elsevier Ltd. All rights reserved.