OBJECTIVE Midface distraction osteogenesis has been popularized for the correction of midface hypoplasia associated with exophthalmos and obstructive sleep apnea in patients with Crouzon syndrome. The purpose of this study was to present the method of utilizing the modified external device with elastic distraction for the midface advancement in Crouzon syndrome, and the clinical outcomes and skeletal changes were analyzed. METHODS Five consecutive patients with Crouzon syndrome underwent Le Fort III osteotomy with midface advancement using a modified external device with elastic distraction. The distraction system consists of a rigid external distractor, nickel-titanium shape memory alloy spring, and bone-borne traction hooks. The midface advancement was initiated with the bony anchorage around the nasomaxillary buttress at the level between occlusal plane and infraorbital margin. The device was activated at a rate of 1 to 1.5 mm per day by the length of spring. The skeletal changes were analyzed by cephalometric and computed tomographic measurement. RESULTS All the patients achieved improvements in midface appearance, obstructive sleep apnea, exophthalmos, and occlusion. No complications occurred during this procedure. After the distraction, 1 patient developed an open bite that was corrected by a definitive orthognathic surgery. Cephalometric and computed tomographic measurement analysis showed a differential advancement of midface with more at the occlusal level than the orbital level. In addition, midface suture and bone remodeling was also observed in growing patient. CONCLUSIONS Our modified external device with elastic distraction offers an alternative method to achieve midface advancement in patients with Crouzon syndrome.