Subacute sclerosing panencephalitis, a progressive neurodegenerative disorder of the central nervous system, can present atypically with uncharacteristic electroencephalographic (EEG) features at its onset albeit typically with progressive mental deterioration, behavioral changes, and myoclonic jerks. An atypical presentation of subacute sclerosing panencephalitis can lead to a delay in diagnosis, thus hindering early treatment. Herein, we describe a 14-year-old girl who presented with insomnia, amnesia, auditory and visual hallucinations. The patient's electroencephalography on admission showed an alpha coma pattern. In spite of antipsychiatric treatment (olanzapine 20 mg/d) for 3 months, a progressive deterioration in neurologic function was observed. Subacute sclerosing panencephalitis was suspected and diagnosis was confirmed by increased titers of measles antibodies in the cerebrospinal fluid. The attention of pediatricians should be drawn to psychiatric symptoms as possible initial presentations of subacute sclerosing panencephalitis in order to avoid needless diagnostic and treatment procedures.