OBJECTIVE: To evaluate dental arch relationship in preschoolers with unilateral cleft lip and palate after early alveolar bone grafting (ABG). MATERIALS AND METHODS: Three raters blindly assessed the dental arch relationship with the GOSLON Yardstick (using a 5-point scale, from 1--very good to 5--very poor outcome) in Early-grafted group (27 boys and 15 girls; mean age = 5.2 years, SD 0.5) and Non-grafted group (17 boys and 12 girls; mean age = 5.8 years, SD 0.8). The groups differed regarding the age when ABG was performed: between 2 and 4 years (mean = 2.4, SD 0.6) in the Early-grafted group and after 9 years in the Non-grafted group. The strength of agreement of rating was evaluated with kappa statistics. RESULTS: The intra- and inter-rater agreement was high (kappa > 0.800). The mean GOSLON score in the Early-grafted group was 2.72 and in the Non-grafted group -2.64. The distribution of the GOSLON grades in the Early-grafted group was: 54.8% had a score 1 or 2, 23.8%--3, and 21.4%--4 or 5; in the Non-grafted group, 38.0% subjects scored 1 or 2, 41.4%--3, and 20.6%--4 or 5 (p = 0.023). CONCLUSIONS: Early alveolar bone grafting carried out between the ages of 2 and 4 years was not found to negatively affect dental arch relationship by the age of 5 years. However, it is possible that such a negative effect could be found if a longer observation period (e.g. at age 10 years or age 15 years) was allowed.