Amitabh Dash,1 Sangeeta Ravat,2 Avathvadi Venkatesan Srinivasan,3 Ashutosh Shetty,4 Vivek Kumar,5 Renu Achtani,6 Vivek Narain Mathur,7 Boby Varkey Maramattom,8 Veeresh Bajpai,9 Nanjappa C Manjunath,10 Randhi Venkata Narayana,11 Suyog Mehta12 1Eisai Co. Ltd., 2Department of Neurology, Seth GS Medical College & KEM Hospital, Mumbai, 3Department of Neurology, Trinity Acute Care Hospital, Chennai, 4Department of Neurology, Criticare Multispeciality Hospital & Research Centre, Mumbai, 5Department of Neurology, Metro Multispeciality Hospital, Noida, 6Department of Neurology, Mata Chanan Devi Hospital, New Delhi, 7Department of Neurology, Vivekananda Hospital, Hyderabad, 8Department of Neurology, Lourdes Hospital, Kochi, 9Department of Neurology, Sai Neurology Clinic, Lucknow, 10Department of Neurology, Brain and Nerve Care, Bangalore, 11Department of Neurology, Seven Hills Hospital, Visakhapatnam, 12Department of Pharmacology & Therapeutics,Government Medical College, Solapur, India Abstract: A prospective, multicentric, noncomparative open-label observational study was conducted to evaluate the safety and efficacy zonisamide in Indian adult patients for the treatment of partial, generalized, or combined seizures. A total of 655 adult patients with partial, generalized, or combined seizures from 30 centers across India were recruited after initial screening. Patients received 100 mg zonisamide as initiating dose as monotherapy/adjunctive therapy for 24 weeks, with titration of 100 mg every 2 weeks if required. Adverse events, responder rates, and seizure freedom were observed every 4 weeks. Efficacy and safety were also assessed using Clinicians Global Assessment of Response to Therapy and Patients Global Assessment of Tolerability to Therapy, respectively. Follow-up was conducted for a period of 24 weeks after treatment initiation. A total of 655 patients were enrolled and received the treatment and 563 completed the evaluation phase. A total of 20.92% of patients received zonisamide as monotherapy or alternative monotherapy and 59.85% patients received zonisamide as first adjunctive therapy. Compared with baseline, 41.22% of patients achieved seizure freedom and 78.6% as responder rate at the end of 24 week study. Most commonly reported adverse events were loss of appetite, weight loss, sedation, and dizziness, but discontinuation due to adverse events of drug was seen in 0.92% of patients. This open label real-world study suggests that zonisamide is an effective and well-tolerated antiepileptic drug in Indian adults for treatment of partial, generalized as well as combined seizures type. No new safety signals were observed. Keywords: zonisamide, partial onset seizures, generalized seizures, responder rate, monotherapy, adjunctive therapy