This study aimed to evaluate the results of maxillary advancement by using internal Le Fort 1 distractors on six patients with unilateral cleft lip and palate who had maxillary hypoplasia.The retrognathic maxilla of five patients were protracted with distractor bilaterally, and asymmetric advancement was performed in one patients. A removable intraoral acrylic appliance was used as an anchorage appliance in two patients, and Ragno fan-type expander appliance was used in the others to prevent maxillary collapse during the distraction period. The maxilla of one patient was not distracted successfully due to the maxillary collapse in result of breaking the removable anchorage appliance away. Lateral cephalograms were evaluated before 3 and 12 months after distraction.A desired level of advancement was attained in five patients. In one patient distraction was not performed due to the maxillary collapse. In one of the five patients with a wide oronasal fistula, the size of the fistula was decreased with asymmetric advancement of right and left maxillary segments. Following the retention period of 12 months, the results were stable. Copyright © 2007 Muntaz B. Habal, MD.