The focus for this clinical review is under-prescribing and non-adherence to medication guidelines in older adults after coronary artery bypass grafting (CABG) surgery. Non-adherence occurs in all age groups, but older adults have a unique set of challenges including difficulty hearing, comprehending, and remembering instructions; acquiring and managing multiple medications; and tolerating drug-drug and drug-disease interactions. Still, non-adherence leads to increased morbidity, mortality, and costs to the healthcare system. Factors contributing to non-adherence include failure to initiate therapy before hospital discharge; poor education about the importance of each medication by hospital staff; poor education about medication side effects; polypharmacy; multiple daily dosing; excessive cost; and the physician's lack of knowledge of clinical indicators for use of medications. To improve adherence, healthcare systems must ensure that (i) all patients are prescribed the appropriate medications at discharge; (ii) patients fill and take these medications post-operatively; and (iii) patients continue long-term use of these medications. Interventions must target central administrative policies within healthcare institutions, the difficulties facing providers, as well as the concerns of patients. Corrective efforts need to be started early during the hospitalization and involve practitioners who can follow patients after the date on which surgical care is no longer needed. A solid, ongoing relationship between patients and their primary-care physicians and cardiologists is essential. This review summarizes the post-operative medication guidelines for CABG surgery, describes barriers that limit the adherence to these guidelines, and suggests possible avenues to improve medication adherence in older cardiac surgery patients.