Aims: Older adults are vulnerable to medication-related harm mainly due to high use of medications and inappropriate prescribing. This study aimed to investigate the associations between inappropriate prescribing and number of medications identified at discharge from geriatric rehabilitation with subsequent post-discharge health outcomes. Method: REStORing health of acutely unwell adulTs (RESORT) is an observational, longitudinal cohort study of geriatric rehabilitation inpatients. Potentially inappropriate medications (PIMs) and potential prescribing omissions (PPOs) were measured at acute admission, and at admission and discharge from geriatric rehabilitation, using version 2 of the STOPP/START criteria. Results: 1890 patients (mean age 82.6 ± 8.1 years, 56.3 % females) were included. The use of at least 1 PIMs, or PPOs at geriatric rehabilitation discharge were not associated with 30-day and 90-day readmission and 3-month and 12-month mortality. Central nervous system (CNS)/psychotropics and fall risk PIMs were significantly associated with 30-day hospital readmission (adjusted odds ratio (AOR) 1.53; 95%CI 1.09─2.15), and cardiovascular PPOs with 12-month mortality (AOR 1.34; 95%CI 1.00─1.78). Increased number of discharge medications was significantly associated with 30-day (AOR 1.03; 95%CI 1.00─1.07) and 90-day (AOR 1.06; 95%CI 1.03─1.09) hospital readmissions. The use and number of PPOs (including vaccine omissions) were associated with reduced independence in instrumental activities of daily living scores at 90-days post geriatric rehabilitation discharge. Conclusion: The number of discharge medications, CNS/psychotropics and fall risk PIMs were significantly associated with readmission, and cardiovascular PPOs with mortality. Interventions are needed to improve appropriate prescribing in geriatric rehabilitation patients to prevent hospital readmission and mortality.