Pediatric Epilepsy Study

INCLUSION CRITERIA: To enter this study, patients must: * Have a diagnosis of partial seizures * Be willing to be hospitalized * Weigh a minimum of 6.6 pounds * Be taking a stable dose of one to two concomitant anti-epileptic medications * Have had a previous CAT scan/MRI confirming the absence of space occupying lesions or progressive neurological disease * Have normal laboratory results EXCLUSION CRITERIA: To enter this study, a patient must not have or be: * Seizures caused by metabolic disturbance, toxic exposure, or active infection * A primary diagnosis of generalized epilepsy (exception - secondarily generalized seizures) * A history of status epilepticus within 30 days * Seizures not related to epilepsy * Frequent use of additional anti-epileptic medications to treat increases in seizures (for example: rectal diazepam) * Taking felbamate within 6 months * Serum sodium levels \<135 mEq/L * Significant heart, breathing, kidney, stomach, liver, blood, or cancer disorder requiring treatment/therapy * A history of chronic infection (e.g., hepatitis or HIV) * Significant electrocardiogram (ECG) abnormalities * A nursing mother taking anti-convulsant drugs * Previously demonstrated sensitivity/allergic reaction to Trileptal or related compounds * Used experimental medication within 30 days of entering this study