The aim of this cross-sectional outcome study using retrospective data capture of treatment histories was to examine the characteristics of young children with unilateral cleft lip and palate who had poor dental arch relationship (i.e., Goslon 5). The study sample comprised 120 children born with nonsyndromic complete unilateral cleft lip and palate between 1995 and 2003, and were aged between 5.0 and 7.0 years (mean age, 5.1 years) at the time of data collection. The dental arch relationship was assessed using the Goslon yardstick from intraoral dental photographs. An independent investigator recorded treatment histories from the clinical notes. The inter- and intraexaminer agreements evaluated by weighted kappa statistics were high. There was no association between dental arch relationship and the type of presurgical orthopedics or pharyngeal flap. Dental arch relationship was associated with the initial cleft size (odds ratio, OR = 1.3; 95% confidence interval, CI = 1.1-1.5, p < 0.01), surgeon grade for palate repair (OR = 5.0, 95% CI = 1.2-19.9, p < 0.05), and primary gingivoperiosteoplasty (OR = 2.8, 95% CI = 1.0-8.1, p = 0.05). These data suggest that intraoral dental photographs provide a reliable method for rating dental arch relationship. Wide initial cleft, high-volume surgeon, and primary gingivoperiosteoplasty are predictors of poor dental arch relationship outcome in young children with unilateral cleft lip and palate. These findings may improve treatment outcome by modifying the treatment protocol for patients with unilateral cleft lip and palate.