To study the bone resorption pattern of iliac crest grafts after thumb reconstruction with a wrap-around flap from the hallux. Patients who underwent thumb reconstruction with a wrap-around flap from the hallux were followed up. We measured the length, proximal, middle, and distal widths, and proximal, middle, and distal thicknesses of the iliac crest grafts on posteroanterior and lateral radiographs and used the length, width, and thickness ratios of the iliac grafts and the first metacarpal bones to calculate the amount of bone resorption. Data from 2 groups reconstructed with or without a terminal tuft were analyzed. Fifteen patients were followed for an average of 20 months (range, 14-72 months). Bone resorption occurred in all 3 measured dimensions in all patients and the degree of resorption increased with time. Resorption amounts of the length dimension in the group with a terminal tuft was significantly decreased compared with those in the group without a terminal tuft at 6 months, 12 months, and the last follow-up. The resorption amount of the width dimension of the distal portion was significantly less in the group with a terminal tuft at the last follow-up. The resorption amount of the thickness dimension of the distal portion was significantly lower in the group with a terminal tuft at 12 months and at the last follow-up. Bone resorption occurred in all dimensions of the graft after thumb reconstruction using a wrap-around flap from the hallux. Flaps including the terminal tuft had less bone resorption in the distal portion. Wrap-around toe flaps should only be used in cases of thumb amputations at the middle of the proximal phalanx and distal, and the terminal tuft should be preserved in the flap; fixation with a plate should be avoided. Therapeutic IV.