The purpose of this retrospective cohort study of older adults with polypharmacy and multimorbidity was to identify patient characteristics associated with new prescriptions for potentially inappropriate medications (PIMs). Patients who are male, 85 years and older, diagnosed with heart disease, and have an increased number of ambulatory visits were most at risk for being newly prescribed PIMs. The authors recommend these characteristics be considered when developing interventions to reduce PIMs in the geriatric population.