A 21-year-old male with SLE developed seizure, loss of consciousness and focal signs referable to involvement of the front-temporal brain regions. MRI (magnetic response imaging) image revealed high signal areas in the temporal lobes. By these findings, herpes simplex encephalitis (HSE) was suspected at first. But neither isolation of herpes simplex virus nor HSV specific IgM by ELISA was detected. Acyclovir administration by intravenous infusion was'nt effective but corticosteroid pulse therapy was effective. The level of anticardiolipin antibody was very high. Finally, the diagnosis of CNS-lupus with HSE-like characteristics was made in this case.