Paraneoplastic neurological syndromes can be associated with the presence of onconeural antibodies. These antibodies are the result of an immune response against a tumour that is ectopically expressing a neuronal antigen. The 'classical' onconeural antibodies (anti-Hu, Yo, Ma2, CRMP-5, amphiphysin and Ri) are directed against intracellular antigens and are strongly associated with underlying malignancy. By contrast, onconeural antibodies directed against cell surface antigens (eg, anti-NMDA, VGKC, AChR) have a weaker tumour association. This article gives a practical overview of the tumour associations, and the neurological associations, of the onconeural antibodies. There is also guidance on how to investigate occult malignancy in antibody positive cases.