Objectives. This study aims to evaluate the effects of methylphenidate (MPH) on eating patterns and body mass index (BMI) in children with attention deficit/hyperactivity disorder (ADHD). The secondary aim of this study is the comparison between weight and eating behavior of children with ADHD undergoing an MPH treatment, and of children without ADHD. Methods. One hundred fourty three children and adolescents who diagnosed with ADHD were enrolled, and the effects of MPH on the eating patterns and BMI were evaluated. All participants completed a number of tests to analyze eating patterns and clinical psychopathological profiles. Results. Children and adolescents with ADHD had significantly higher scores on the EDE-Qeating concern, EDE-Q-shape concern, and all CPRS-RSF subscales than individuals without ADHD (p < .05). MPH treatment was associated with a notional reduction in height-sds and weight-sds. The results of the correlation analysis which assessed the possible contribution of the different treatment-related factors revealed no significant correlations between MPH mean dose [mg/(kg/d)], the duration of use (months), and the core characteristics of eating disorders except the restraint subscale of EDE Q. Conclusions. Our findings add to the growing research suggesting that MPH may be associated with disordered eating behaviors. Although the literature is limited, our findings conclude that MPH may not be associated with the reduction of growth velocity and disordered eating behaviors.