To assess the efficacy, safety, and tolerability of topiramate in infants younger than 24 months of age, we conducted an open-label, multicenter chart review study of infants who received topiramate. Twenty-eight patients were evaluated. All had refractory epilepsy. The mean age of seizure onset was 3.8 months (range 0-10 months). Refractory infantile spasms were the most common epilepsy syndrome. Among infants without infantile spasms, complex partial seizures were the prominent seizure type in eight, followed by simple partial seizures in six. Topiramate was prescribed as add-on therapy in 25 cases and as monotherapy in 3 cases. Seven of the eight infantile spasms cases improved on topiramate therapy, attaining topiramate monotherapy in three infants. Half of the infants with other seizure types responded to topiramate. The average treatment duration among topiramate responders was 11 months. Topiramate was prescribed after a mean of 3.3 antiepilepsy drugs had been used in these infants. In no case was topiramate the first prescribed antiepilepsy drug. Adverse effects occurred only in five patients, leading to topiramate discontinuation in two patients. Topiramate was efficacious and well tolerated in infants younger than 24 months of age with refractory epilepsy. Prospective data are needed to corroborate this observation.