To determine brain functional abnormality in systemic lupus erythematosus (SLE) patients with psychiatric symptoms, we evaluated 12 active SLE patients with or without psychiatric symptoms by means of [18 F] 2-fluoro-2-deoxy-D-glucose positron emission tomography (PET), magnetic resonance imaging and neuropsychological testing. Patients with psychiatric symptoms showed significantly poorer performance in tests which subserved attentional function. The PET study revealed that the psychiatric patients had significantly decreased regional cerebral metabolic rates for glucose in the prefrontal, inferior parietal and anterior cingulate regions. Prefrontal, inferior parietal and anterior cingulate dysfunction may be related to attentional deficits that are involved in various psychiatric symptoms in SLE. PET is an invaluable tool to reveal such brain functional abnormality seen in SLE patients with psychiatric symptoms.