Striatal hypermetabolism on 18FDG-PET scan is a neuroradiological finding that has been described in association with autoimmune disorders such as Sydenham chorea, lupus or antiphospholipid syndrome. Here, we report three patients with non-paraneoplastic limbic encephalitis characterized by 18FDG-PET hypermetabolism of both striata, in contrast with diffuse hypometabolism in the rest of the brain. All patients developed subacute dementia, and antibodies to voltage-gated potassium channels were found in all cases. Brain metabolism and neurological status improved within a few months of immunosuppressive therapy. The finding of striatal hypermetabolism on 18FDG-PET images could thus be highly indicative of limbic encephalitis associated with anti-neuropil antibodies. It could be of significant help in the diagnosis of this rare and treatable condition, and may also provide a useful marker of disease outcome.