Abstract： Objective To assess the efficacy and adverse-event profile of monotherapy oradd-on therapy with topiramate in elderly patients with epilepsy. Methods A multicenter, prospective,open-label, observational study of topiramate, for either monotherapy or add-on therapy, was performedamong 119 elderly patients with epilepsy in the Outpatient Department of Neurology of 52 generalhospitals in China. After the baseline evaluation, topiramate was given at the target dose of 200 mg/dayover an 8-week titration period. In the subsequent 12-week maintenance period, the topiramate dose wasadjusted (200-300 mg) according to the clinical results. The patients were followed up for 6 months, withmonthly visits and regular physical, neurological and laboratory examinations. Results After themaintenance period, 106 patients (89.1%) showed a seizure frequency reduction by 50% or greater fromthe baseline, among whom 65 patients(93.8%)received the monotherapy and 54(83.8%) had the add-ontherapy. Topiramate monotherapy and add-on therapy resulted in a complete seizure control in over 50%of the patients with various types of seizure. In patients with disease course less than 1 year, between 1and 3 years, between 4 and 6 years, and over 6 years, topiramate monotherapy resulted in seizurereduction by 92.86%, 91.67%, 100%, and 94.44%, and the add-on therapy reduced the seizure by80.00%, 85.71%, 70.00%, and 86.36%, respectively. When combined with carbamazepine, valproatesodium, phenytoin, phenol barbital, and diazepam, the total effective rate oftopiramate was 79.41%,87.50%, 85.71%, 0%, and 80.00%, respectively. Topiramate, especially in monotherapy, caused onlymild or moderate adverse effects. Conclusion Topiramate is effective and safe for either monotherapyor add-on therapy of epilepsy in elderly patients. The types of epilepsy, disease course, or the drugs usedin the add-on therapy do no obviously affect the efficacy of topiramate for seizure control.