OBJECTIVE To analyze the long-term effect of mandibular bone as donor material in bone grafting of the alveolar process defect in patients with unilateral cleft lip and palate (UCLP), compared with iliac crest cancellous bone. METHODS During a 7-year period, 101 UCLP patients were bone grafted, 57 cases with iliac crest cancellous bone and 44 with mandibular symphyseal bone. The long-term results with an observation time of more than 4 years were analyzed with respect to marginal bone level and dental and gingival condition in the grafted area. Complications were recorded. RESULTS The bone level in the grafted area was satisfactory in both groups. Impaction of cleft-side canines was found in 35% of the patients in both groups. Patients with agenesis of the cleft side lateral incisor had significantly more impacted canines, compared with patients with a cleft-side lateral situated in the lesser maxillary segment, probably due to the fact that the lateral incisors help in guiding the canine down through the grafted area. The number of complications was scarce, although both groups demonstrated some gingival retraction with a longer crown length at the cleft side central incisor. CONCLUSIONS The findings of this study have changed our strategy in bone grafting. Timing of orthodontic treatment and bone grafting has been more varied depending on the position and presence of teeth in the cleft area. Bone grafting of the alveolar process is not just a local treatment of a bony defect, but in respect to the burden of treatment, bone grafting of the alveolar process has to be planned in accordance with orthodontic treatment and maxillofacial growth.