Paraneoplastic neurological disorders associated with onconeural antibodies often appear with neuropsychiatric symptoms. To study the prevalence of onconeural antibodies in patients admitted to acute psychiatric inpatient care, the serum of 585 such patients was tested for antibodies targeting MOG, GLRA1B, DPPX, GRM1, GRM5, DNER, Yo, ZIC4, GAD67, amphiphysin, CV2, Hu, Ri, Ma2, and recoverin. Only one sample was positive (antirecoverin IgG). The present findings suggest that serum onconeural antibody positivity is rare among patients acutely admitted for inpatient psychiatric care. The clinical implications of this finding are discussed.