The prevalence of hallucinations and delusions was studied in 1,715 patients with unipolar or bipolar affective disorders hospitalized at a tertiary care facility. The authors found that the presence of psychotic features was significantly associated with diagnostic subtype. Bipolar manics were more likely than primary depressives, secondary depressives, and bipolar depressives to have hallucinations and/or delusions; primary depressives were significantly more likely than secondary depressives to have psychotic features. Among psychotic patients, bipolar manics were more likely than the other diagnostic groups to have delusions only and less likely to have hallucinations only. Possible explanations for these findings are discussed.