Older persons with mental disorder need mental health services, but the extent to which they have service needs in other domains (medical, functional and psychosocial) is not established, although these needs may compromise the attainment of psychiatric outcomes. This study focuses on 169 older adults hospitalized for depression and documents their post-acute service needs in four domains: psychiatric, medical, functional and psychosocial. Seventy-five per cent of these psychiatric patients had medical conditions that required treatment. Eighty-four per cent needed assistance with routine activities. Nearly two-thirds (67%) were experiencing one or more psychosocial or environmental problems that warranted intervention. The mean number of service needs was 6.5 (SD = 1.5). Fifty-seven per cent had needs in all four domains. Older adults admitted to acute care for depression have high levels of service needs stemming from multiple domains: psychiatric, medical, functional and psychosocial. We extend the biopsychosocial model, largely used to address the origins of psychopathology, to conceptualize the multiple domains of service that older adults with mental disorder need. This biopsychosocial model suggests that needs in each domain should be identified and addressed if desired psychiatric outcomes are to be attained.