An intra-oral appliance has been developed that appears to exploit the anteroposterior adjustment potential of the maxillary sutures in the unilateral cleft lip and palate infant. In the treatment of the depressed alar base and dental arch malalignment in six infants, activation of the appliance produced a forward repositioning of the entire cleft maxilla, levelling of the alar bases, and improvement of arch form in a period of from 9 to 20 days. The new positions were retained for at least 10 days, and the appliance was removed one week before surgery. Continued evaluation of the method appears to be warranted.