OBJECTIVE To compare two treatments for unilateral cleft lip and palate. METHODS Follow-up study. METHODS University department, Germany. METHODS 110 children with unilateral cleft lip and palate, 50 of whom were treated between 1980 and 1988 (group 1) and 60 of whom were treated between 1970 and 1979 (group 2). METHODS Group 1 had no dentofacial treatment before operation. At the age of 3 months they had musculoperiosteal reconstruction with no orthopaedic treatment postoperatively. At the age of 9-12 months they had the velar muscle reconstructed but no orthopaedic treatment to follow. Group 2 had dentofacial treatment before operation. At the age of 6 months they had their lips operated on by Millard's technique. Postoperatively they had dentofacial orthopaedic treatment followed, at the age of 2.5 years, by palatal surgery by the Campbell-Widmaier technique. This was followed by more dentofacial orthopaedic treatment. Main outcome measure--Growth of the midface skeleton. RESULTS The course of the anterior tooth segment was similar in the two groups, as was the transverse development of the maxilla. Analyses of both dental casts and lateral cephalometric radiographs showed that the skeletal development in group 1 (who had undergone reconstruction of the perioral and perinasal muscles) was better than in group 2 (who had not) despite the fact that group 1 had had no orthopaedic growth stimulation. CONCLUSIONS If the primary and secondary growth centres are not joined at the first operation and the midfacial muscles are not reconstructed, even orthopaedic growth stimulation will not compensate for the defect.