Methylphenidate (MPH), the first line medication treatment of attention deficit hyperactivity disorder (ADHD), may be associated with behavioral adverse effects. Amongst these reactions, psychotic symptoms are the most challenging ones for clinicians. For ADHD patients with suboptimal symptom control, switching MPH formulations may be helpful. The possible differences in the risk of adverse effects between long acting MPH formulations is largely unknown. Hereby, we report a child case who developed psychotic symptoms when switching from osmotic release oral system (OROS) MPH to modified-release MPH. [Anadolu Psikiyatri Derg 2017; 18(4.000): 410-412]