Introduction: The purpose of this study was to investigate the differences in the prevalence of cleft sidedness, the number of congenitally missing or malformed permanent maxillary lateral incisors (MLIs), and the presence of supernumerary teeth in Korean patients with unilateral cleft lip and alveolus (UCLA) and those with unilateral cleft lip and palate (UCLP). Methods: Seventy-five patients with UCLA and 129 patients with UCLP (ages, 6.0 to 13.0 years) were studied by using their charts, models, radiographs, and intraoral photographs. The chi-square test, the binomial test, and the relative risk assessment were used. Results: There was a male dominant tendency in both UCLP ( P <.001) and UCLA ( P <.05) patients. The UCLP patients were 1.3 times more involved on the left side and had 2.2 times more congenital missing MLI than did the UCLA patients. When an MLI was present, malformation occurred more frequently than normal shape in the UCLA ( P <.001) and UCLP ( P <.01) patients. Incidence of supernumerary teeth was 4.6 times higher in UCLA than in UCLP patients. Conclusions: When the cleft extended to the secondary palate, left-sided involvement was more predominant than in UCLA patients. When cleft involvement was confined to the primary palate, present MLIs were more common than congenitally missing teeth, and supernumerary teeth were more prevalent than in UCLP patients. These are important characteristics to be considered in the diagnosis and treatment planning of cleft patients.