The authors evaluated zonisamide for symptomatic infantile spasms in 23 patients. Spasm cessation, EEG evolution, and tolerability were assessed for a mean duration of 6.5 months. Six patients (26%) had complete control with cessation of spasms and clearing of hypsarrhythmia. Mean latency time from onset of zonisamide treatment to complete spasm control was 19 days. There were no discontinuations due to adverse effects.