The prevalence of psychiatric disorders among new admissions to nursing homes is unknown. Such data are needed to estimate the psychiatric needs of this population. We report the prevalence of specific psychiatric disorders in 454 consecutive new nursing home admissions who were evaluated by psychiatrists and diagnosed according to the Diagnostic and Statistical Manual of Mental Disorders, third edition, revised. Eighty percent had a psychiatric disorder. The commonest were dementia syndromes (67.4%) and affective disorders (10%). Also, 40% of demented patients had additional psychiatric syndromes such as delusions or depression, and these patients constituted a distinct subgroup that predicted frequent use of restraints and neuroleptics, and the greatest consumption of nursing time. These data demonstrate that the majority of nursing home residents have psychiatric disorders on admission, and that their management is often quite restrictive. Research is now needed to determine the best methods of treatment for nursing home patients with mental disorders.