This study evaluated the early changes of maxillary alveolar arches of operated unilateral cleft lip and palate patients. Dental casts were available at four age increments. Triangular flap cheiloplasty was carried out at an early age. Two-stage palatoplasty by vomer flap and soft palate closure took place later. Prior to lip repair, the alveolar arches were classified according to the relationship between greater and lesser segments. Almost a quarter had overlap of the alveolar segments with no contact between the alveolar ridges at the cleft site; some had no overlap with contact of the alveolar segments in the cleft region; almost a quarter had both overlap of the alveolar segments and contact; and almost half had no overlap of the segments and the alveolar ridges were not in contact at the cleft site. After lip repair, the arch relationships were examined and the percentage of patients in each of the four groups indicated a moulding effect of lip repair on the alveolar segments. This moulding effect caused the alveolar segments in most patients to be in contact at the cleft site. Most of these also had segment overlap. All patients were re-examined shortly after palatal repair. The trend for segment overlap and contact continued after palate surgery. However, when all patients were seen at age 4, percentages of patients in each group indicated that previous overlap of segments improved to a more desirable nonoverlapped relationship in approximately half of the patients. The other half continued to demonstrate arch collapse, in excess of what would be considered ideal ridge relationship.