The aim of this study was longitudinally to evaluate the treatment results after secondary bone grafting in 224 cleft patients with an observation period of more than four years. The patients were divided into three groups according to age and eruption stage of the canine at the time of surgery. Group A included 94 patients with a mean age of 10 years, operated before eruption of the canine; group B included 72 patients with a mean age of 13.1 years operated after eruption of the canine; and group C included 58 patients operated after the age of 16 years (mean age, 20.4 years). The evaluation of the treatment results included longitudinal comparison of marginal bone level, periodontal status on cleft-related teeth, dental status in the bone grafted region, esthetical and functional properties of the reconstructed alveolar process, as well as the influence on growth of the maxilla. The marginal bone level was found to be significantly higher among unilateral cleft lip and palate (UCLP) and bilateral cleft lip and palate (BCLP) patients in the youngest groups as compared to the other groups. The number of UCLP and BCLP patients who could be treated without bridgework was significantly higher in the youngest age group than in the other groups, as were the esthetic and functional properties of the reconstructed alveolar process. External root resorption occurred in 17 patients in groups B and C. No influence of the procedure on sagittal growth of the maxilla could be demonstrated, whereas the anterior facial height was reduced.(ABSTRACT TRUNCATED AT 250 WORDS)