There is a lack of clinical trials on pediatric dental sedation in children 3 years old and under. We investigated whether young children's behavior improves during dental treatment with combined oral ketamine and midazolam compared to midazolam alone or no sedation. Healthy children under 36 months of age, presenting early childhood caries and referred to a pediatric dental sedation clinic were randomly assigned to receive combined midazolam (0.5 mg/kg) and ketamine (3 mg/kg) (MK), oral midazolam (1.0 mg/kg) (MS), or protective stabilization without sedative (PS). One observer scored children's behavior using the Ohio State University Behavior Rating Scale (OSUBRS) at determined points in a dental exam (no sedative) and treatment session. Data were analyzed using non-parametric bivariate tests.