A lip-adhesion procedure before definitive repair of unilateral complete cleft lip has been widely used but rarely analyzed over the past 25 years. This report is a quantitative prospective assessment of one possible benefit of lip adhesion, an increased vertical height of the cleft labial elements. Lip adhesion was performed on 43 consecutive infants with unilateral complete cleft of the primary palate. Markings for rotation-advancement repair were placed before lip adhesion and again at the time of the complete nasolabial correction. Using a standardized caliper, anthropometric measurements of the vertical height of the medial and lateral lip elements were made from these markings. The relative increase in vertical height of the medial and lateral labial segments during the mean interoperative interval of 3.2 months was calculated. Analysis of these measurements revealed a small disproportionate increase in vertical lip height of the cleft side compared with the normal side after lip adhesion. Discrepancy of the lateral lip height between the cleft and noncleft sides decreased from 3.0 to 2.7 mm (10 percent, p = 0.05), and the prolabial or medial height discrepancy decreased from 3.4 to 2.8 mm (17 percent, p < 0.01). Subgroup analysis of infants whose adhesion was done either at a young age, without premaxillary orthopedics, or with an intact secondary palate, revealed no statistically significant improvement in the labial height measures. It is arguable whether the small relative increase in height of the medial and lateral cleft elements justifies lip adhesion before definitive repair of unilateral complete cleft lip.