Aim Family function is an essential factor affecting older adults' health. However, there has been no appropriate method to assess the family function of most older adults with fragility or poor health status. The present study aimed to explore the differences and relevance of family function estimated by home care nurses and the older adults, and to determine if nurses could represent older adults to provide the estimation. Methods Study participants were 50 older adults who were aged older 65 years and were taken care of at home by well‐trained nurses. The present study used the Family APGAR as the questionnaire. We compared the results evaluated by the older adults and their home care nurses. The results included the level of dysfunction and the total scores of the questionnaire. The paired t‐test and McNemar–Bowker test were used for the analysis. Results Family function could be leveled as “good,” “moderate dysfunction” and “severe dysfunction” according to the scores. The family function levels estimated by nurses showed no significant differences to the patients' condition (P = 0.123 > 0.05). Comparing the total scores of the older adults with those of their own home care nurses, the results showed a moderate to nearly high correlation (R = 0.689/P < 0.001). Caring time might be the factor affecting the result. Conclusions The present study provides a way of helping physicians to ascertain older adults' family problems much earlier and to improve the their health status by enhancing family support. Geriatr Gerontol Int 2015; ●●: ●●–●●.