We report a case of paraneoplastic limbic encephalitis (PLE) in an elderly lady with small-cell lung carcinoma (SCLC) and positive anti-RI neuronal auto-antibody. PLE is a relatively rare clinical entity associated with cancer patients, but is probably under-diagnosed. PLE typically presents clinically with affective changes in personality, cognitive dysfunction and seizures in a patient with malignancy, particularly SCLC. Although diagnosis does not rely upon definitive investigation results, serum paraneoplastic antibodies, abnormal CSF, and characteristic MRI and EEG findings may support the diagnosis. As PLE often presents prior to the discovery of a primary tumour, knowledge of the disease may assist in identifying underlying malignancy.