Objective: To test the hypothesis that sagittal maxillary growth hypoplasia has no effect on mandibular asymmetry among subjects with complete unilateral cleft lip and palate (UCLP). Design: A total of 86 subjects (normal noncleft, 42; UCLP, 44) in the age range of 15 to 25 years were chosen. Normal noncleft subjects were included in Group I. Based on the severity of sagittal maxillary growth hypoplasia, subjects with UCLP were divided into two groups. Subjects with UCLP in whom the SNM angle was ≥71 degrees and the M-point to Nasion perpendicular distance was ≤-210 mm were included in Group II. Group III consisted of subjects with UCLP in whom the SNM angle was <71 degrees and the M-point to Nasion perpendicular distance was >-210 mm. The mandibular asymmetry index (condylar, ramal, and condylar+ramal), gonial angle, and depth of the antigonial notch of three groups of subjects were examined on orthopantomograms (OPGs). Results: Among Group II subjects in whom sagittal maxillary growth was near normal, ramal and condylar+ramal heights were significantly less on the cleft side than on the normal side (P <.01). Condylar, ramal, and condylar+ramal asymmetry indices were significantly greater among Group II subjects. Mandibular asymmetry indices among Group III subjects were comparable with those in Group I subjects. Conclusion: The hypothesis was rejected. The mandible was significantly asymmetrical among subjects with UCLP in whom sagittal maxillary growth was near normal, whereas the mandible was nearly symmetrical among subjects with UCLP in whom sagittal maxillary growth hypoplasia was very severe. © 2011 by The EH Angle Education and Research Foundation, Inc.