Unplanned hospitalizations from nursing homes (NHs) may be considered potentially avoidable and can result in adverse resident outcomes. There is little information about the relationship between a clinical assessment conducted by a physician or geriatric nurse expert before hospitalization and an ensuing rating of avoidability. This study aimed to describe characteristics of unplanned hospitalizations (admitted residents with at least one night stay, emergency department visits were excluded) and to examine this relationship. We conducted a cohort study in 11 Swiss NHs and retrospectively evaluated data from the root cause analysis of 230 unplanned hospitalizations. A telephone assessment by a physician (p=.043) and the need for further medical clarification and treatment (p=<0.001) were the principal factors related to ratings of avoidability. Geriatric nurse experts can support NH teams in acute situations and assess residents while adjudicating unplanned hospitalizations. Constant support for nurses expanding their clinical role is still warranted.