Introduction: Attention Deficit Hyperactivity Disorder (ADHD) is the most common neurobehavioral disorder of childhood. Treatment strategy includes pharmacological and psychosocial approach. Stimulant medication is the first choice among pharmacological management. Various formulations of Methylphenidate are immediate release, extended release and osmotic release oral system. Aims & Objectives: To compare the clinical outcome of children with ADHD on different formulations of methylphenidate in terms of improvement in core symptoms, and tolerability and side effects. Methods: It was a prospective analytic study. Study subjects were90 children with ADHD in the age group between 6 and 16 years, who were prescribed different formulation of Methylphenidate ie. Immediate release (MPH-IR), Extended release (MPH-ER) and Osmotic Release Oral System formulations (MPH-OROS), on 1:1:1 basis randomly to form 3 groups.After 3 months of pharmacological and behavioral therapy, these children were re-assessed on Conner’s parent rating scale to compare the outcome on behavioral performance. Tolerability and side effects of drugs were compared on the basis of a pre-designed questionnaire completed by the parents. Results: All the three groups of Methylphenidate showed significant reduction in scores of inattention (p value=0.00) and significant reduction in scores of hyperactivity (p value=0.04). On comparing each group, long acting MPH-ER and MPH-OROS showed better outcome than short acting MPH-IR (p value=0.04). Out of 90, only 33 subjects complained of adverse effects which was statistically not significant (p value =0.798). Conclusion: In the treatment of ADHD, once-daily MPH-ER and MPH-OROS showed significant improvements in behaviour, better than MPH-IR with a favourable side effect profile and a prolonged duration of effect.