The aim of this study was to evaluate the efficacy and safety of zonisamide monotherapy in a cohort of children and adolescents with various types of epilepsy. Retrospective review of charts of our institution from 2001 through 2004 identified 69 children (19 males and 50 females, mean age 13.2 years) with epilepsy on zonisamide monotherapy. Seizure count and side effect profile were maintained during therapy. Sixty-one percent had idiopathic generalized epilepsy, 4% symptomatic generalized epilepsy, and 35% partial-onset epilepsy. Zonisamide was the first-line and second-line monotherapy for 32% and 68% of patients, respectively. The mean duration of follow-up on treatment was 22 months (range 3-48 months). The overall efficacy of zonisamide was 75.4% (> or = 50% seizure frequency reduction: good responders). Sixty-seven percent of good responders became seizure-free. Seventy-nine percent of patients with partial epilepsy and 71% with generalized epilepsy were good responders, of whom 79% and 63% were free of seizure, respectively. Eighteen (26%) patients developed side effects: weight loss (9), cognitive impairment (3), sleepiness (3), dizziness (2), and decreased appetite (1). In seven patients (10%), zonisamide had to be discontinued: four due to side effects and three because of poor seizure control. Zonisamide was demonstrated to be effective as monotherapy in children with epilepsy.