This long-term study was a follow-up of 46 patients with complete unilateral cleft lip and palate treated with secondary or late secondary bone grafting. Surgeons with different degrees of experience in this procedure had operated on these patients. Morphology of the clefts prior to the grafting was assessed with regard to width of cleft, stage of eruption of permanent canine, presence or absence of permanent lateral incisor and position of permanent lateral incisor and permanent canine in the dental arch. Outcome of surgery was evaluated with regard to the amount of bleeding, flap dehiscence, alveolar bone height, and space closure in the previous cleft area. Dehiscence rate was 23% (11) and total failure rate 4% (2). Alveolar bony height in 38 patients (81%) was more than 75% of the normal alveolar bone height; in 6 cases (13%) between 50-75% bone height and in 3 subjects (6%) surgery had given less than 50% of the normal bone height. Cleft space was closed by orthodontic means in 49% of patients. Best results were obtained when bone grafting was performed prior to canine eruption. Furthermore, significantly better results regarding alveolar bone height were obtained by the more experienced surgeons.