The pedicled buccal fat flap has recently been applied to cover the lateral raw surfaces during palatoplasty as an attempt to mitigate scar-induced transverse maxillary constriction during growth, but with no formal long-term comparative analysis. This three-dimensional imaging-assisted study assessed its impact on posterior transverse maxillary development. Cone beam computed tomographic scans from patients with unilateral cleft lip, alveolus, and palate who received buccal fat flap (buccal fat group; n = 22) or Surgicel (Surgicel group; n = 32) for covering lateral raw surfaces during modified Furlow palatoplasty at 9 to 10 months of age and had reached the age of 9 years were retrieved for analysis. Patients with unilateral cleft lip and alveolus (nonpalatoplasty group; n = 24) were also included for comparison. Using three-dimensional maxillary image models, linear (U6T-MSP and U6J-MSP) and area measurements were calculated for cleft and noncleft posterior maxillary sides and for total posterior transverse maxillary dimension. The buccal fat group had significantly (all p < 0.05) wider dimensions compared with the Surgicel group for all transverse maxillary measurements on both the cleft and noncleft sides, except for U6J-MSP and posterior palatal area parameters on the cleft side ( p > 0.05). The buccal fat group had significantly (all p < 0.05) wider total transverse maxillary dimensions compared with the Surgicel and nonpalatoplasty groups. Covering the lateral raw surfaces with buccal fat flaps resulted in less posterior transverse maxillary constriction compared with the Surgicel-based covering procedure. Therapeutic, III.