Bone-grafts were evaluated in 45 patients with uni- or bilateral residual alveolar clefts. In this population there were 31 unilateral clefts and 14 bilateral clefts. This makes a total of 59 bone grafts. The mean follow-up period was 5.7 years. The patients were divided into two groups. Group A (grafting prior to the eruption of the homolateral canine) and group B (grafting after the eruption of the homolateral canine). Group A consisted of 38 grafts in 30 patients and group B consisted of 21 grafts in 15 patients. The grafts were harvested from the iliac crest. The alveolar bone-height was evaluated on occlusal radiographs. Results in patients treated prior to the eruption of the homolateral canine were significantly better then in patients treated after eruption of the canine. No difference was found between unilateral or bilateral clefts. Of the 38 canines which had not erupted at the time of the grafting procedure 26 (68.4%) erupted spontaneously.