Background: Older patients are usually assessed by occupational therapists in hospital before going home. However, for many frail older adults, this assessment in an unfamiliar environment might not be as representative of their functional abilities as an assessment at home. The aim of this literature review was to determine if differences exist between home and clinical instrumental activities of daily living (IADL) assessments of frail older adults and identify factors that might explain those differences, if any. Method: The sources of the review data were Medline, CINAHL, AMED, PsycINFO, Embase and Current Content from 1988 to 2008. As few relevant studies concerning frail people were found, the search was extended to mixed-age and older adult populations. Ten articles were retained. Main findings: The results suggest differences in IADL assessment between settings for older adults without dementia. Some factors, such as familiarity with the environment and coping skills, might explain those differences. Based on this review, similar results might be expected with frail older people. Implications for practice: Given the dearth of literature on this topic, further research is needed to compare home and clinical assessments and measure relevant factors in a frail population. Helping occupational therapists to identify frail patients, who may show different abilities in unfamiliar settings, could mean more appropriate services after discharge from hospital.