OBJECTIVE To compare the effectiveness between parent-child interaction therapy (PCIT) and methylphenidate in preschool children with attention-deficit/hyperactivity disorder (ADHD) symptoms and disruptive behaviors who had remaining significant behavior problems after previous behavioral parent training. METHODS We included 35 preschool children, ranging in age between 3.4 and 6.0 years. Participants were randomized to PCIT (n = 18) or methylphenidate (n = 17). Outcome measures were maternal ratings of the intensity and number of behavior problems and severity of ADHD symptoms. Changes from pretreatment to directly posttreatment were compared between groups using two-way mixed analysis of variance. We also made comparisons of both treatments to a nonrandomized care as usual (CAU) group (n = 17) regarding intensity and number of behavior problems. All children who started one of the treatments were included in the analyses. RESULTS Mothers reported a significantly more decreased intensity of behavior problems after methylphenidate (pre-post effect size d = 1.50) compared with PCIT (d = 0.64). ADHD symptoms reduced significantly over time only after methylphenidate treatment (d = 0.48) and not after PCIT. Changes over time of children in the CAU treatment were nonsignificant. CONCLUSIONS Although methylphenidate was more effective than PCIT, both interventions may be effective in the treatment of preschool children with disruptive behaviors. Our findings are preliminary as our sample size was small and the use of methylphenidate in preschool children lacks profound safety data as reflected by its off-label status. More empirical support is needed from studies with larger sample sizes.