The cerebral glucose metabolism in eight patients with systemic lupus erythematosus (SLE) and in five healthy controls were examined by positron emission tomography (PET) using 18-F-labeled deoxy-glucose (FDG) as tracer. One of the eight patients had no abnormality by magnetic resonance imaging (MRI), three of them had cerebral atrophy and four patients had multiple white matter hyperintensities and vascular infarcts in the striatum as assessed by MRI. With FDG-PET, inhomogeneous multifocal cerebral glucose hypometabolism was detected, more frequently in the temporal lobe of right hemisphere. The PET findings did not correlate always with the neurological symptoms. Abnormalities in brain metabolism can be detected more frequently by PET, than morphological changes by MRI, indicating the involvement of the central nervous system.