Benign familial neonatal convulsions are a rare, autosomal-dominant form of neonatal epileptic syndrome. It can occur 1 week after birth, and usually involves frequent episodes, but with a benign course. The diagnosis depends on family history and clinical features. The mutant gene locates at 20q13, a voltage-gated potassium-channel gene (KCNQ2). Our patient exhibited an uneventful delivery course and onset of seizures at age 2 days. The general tonic seizures were unique and asymmetric, with frequencies of >20 per day. Results of examinations were within normal limits, including biochemistry and brain magnetic resonance imaging. Abnormalities included a small ventricular septum defect on cardiac sonography unrelated to the seizures, and nonspecific, multiple, high-voltage sharp waves and spike waves occurring infrequently in the central region on electroencephalogram. After phenobarbital and phenytoin use, the seizures persisted. On day 12, another antiepileptic drug, vigabatrin (unavailable in the United States), was used, and seizures decreased. A novel mutation of KCNQ2 was identified from a blood sample. The baby had occasional seizures with drug treatment at age 3 months. Benign familial neonatal convulsion should be considered in a baby with a unique seizure pattern and positive family history. Genetic counseling and diagnosis are mandatory.