The authors report a patient with Lennox-Gastaut syndrome who was a fraternal twin. The twins encountered myoclonic seizures at the age of 4 years, but the seizures in the other patient were controlled very quickly without intellectual development damage. With the disease evolving, other characteristic seizures of Lennox-Gastaut syndrome appeared and failed to be controlled by multiple antiepileptic drugs, so levetiracetam was added on. At this time, frequent partial seizures from the left occipital and posterior temporal regions occurred, which always intermixed with atypical absence seizures in a single ictal event. To control the status epilepticus, levetiracetam was withdrawn immediately, and clonazepam, midazolam, and corticotropin in turn were used. The partial seizures were gradually alleviated. The results obtained in this study suggest that there might be some correlative mechanisms between partial seizures and atypical absence seizures in a single event. There is a temporal relationship between the occurrence of partial seizures and the introduction of levetiracetam.