Lennox-Gastaut syndrome (LGS) is classified as a generalized epilepsy, and is often intractable to antiepileptic drugs. Although corpus callosotomy may sometimes control drop attacks, curative epilepsy surgery is rarely possible in LGS. We report, here, a patient with LGS and focal cortical dysplasia, who became seizure-free after epilepsy surgery. The patient was a 24-month-old boy without perinatal insult in whom seizures began 7 days after birth and who experienced development delay. Brain magnetic resonance imaging (MRI) showed focal cortical lesion with calcification in the right frontal area. At age 13 months, his seizure type changed from tonic seizures to head drops (atonic types) and atypical absence seizures. His interictal electroencephalogram (EEG) showed generalized slow spike and wave discharges, and he was diagnosed with LGS. His seizures were intractable to medical treatment, and a ketogenic diet was not effective. He was evaluated prior to surgery by long-term video-EEG monitoring, which detected many seizures consisted of a sudden onset of falling attacks (atonic type) intermittently followed by atypical absence seizures with diffuse slow wave bursts followed by slow spike and wave discharges in ictal EEG, brain positron emission tomography (PET) and MRI. A right frontal lesionectomy with intra-operative electrocorticography (EcoG) was performed. From the time of lesionectomy to the present, the patient has been seizure free and has been developing normally. Our results suggest that focal resective surgery should be considered in patients with LGS and focal epileptic lesions.