This study examined the effect of medication regimen changes at hospital discharge on adherence and adverse events among older adults. At 30-days post-discharge, nearly half of patients were nonadherent to at least one medication change, 26% visited the emergency department, 6% were readmitted to the hospital, and 0.5% died. Patients who were non-adherent to all medication changes had a 35% higher risk of adverse events within 30-days post-discharge compared to those were adherent to all changes.