To determine differences in maxillary and dentoalveolar relationships between untreated and treated patients having unilateral clefts of the lip and alveolus (UCLA) or lip and palate (UCLP), dental cast assessments were done on 70 untreated adult Indonesian patients (UCLA-I, UCLP-I) and 67 Dutch patients, surgically treated in infancy (UCLA-D, UCLP-D). The Indonesian group consisted of 44 UCLA-I and 26 UCLP-I patients, and the Dutch group of 24 UCLA-D and 43 UCLP-D patients. In the UCLA-I patients, deformities occurred in that part of the dentoalveolar complex that surrounds the cleft. Lip repair in the UCLA-D group more frequently caused deformities in the incisor and buccal areas on the cleft side. In the UCLP-I patients, deformities were present in the incisor and cuspid areas on the cleft side. The buccal segments showed collapse both on the cleft and noncleft sides. Lip and palate repair in the UCLP-D group caused significantly more deformities in the incisor, cuspid, and buccal areas up to the level of the first molars, both on the cleft and noncleft sides. Surgical treatment seems to cause maxillary and dentoalveolar deformities up to the first molars more frequently, but these are not as pronounced as one would expect: following the practiced surgical regimen, the deformities were usually mild. Negative effects of surgical intervention seem to be antagonized by the restored integrity of the lip and palate leading to orientation of maxillary parts and correction of tongue position, which in turn has a molding effect on the maxilla and mandible.