Measures of medication adherence to noninsulin diabetes medications (NIDM), statins, and renin angiotensin system antagonists (RASA) have been continuously used in the star ratings program since 2012. Adherence to these treatments is undoubtedly important. However, the consistent use of these measures in the star ratings program over time has limitations. The purpose of this Viewpoints article is to highlight concerns associated with the current star ratings adherence measures and to offer proposals for the improvement of the adherence measurement in the program. This scoping review outlines concerns with the validity of the 3 star ratings adherence measures. In addition, star ratings data are used to describe payment thresholds for the 3 adherence measures over time to describe concerns associated with their use. Since 2012, there has been significant growth in the proportion of patients considered adherent in the star ratings program. Rates of adherence in a 2-star plan for NIDM (79%), RASA agents (83%), and statins (79%) now exceed what is commonly reported in the clinical literature. For a plan to achieve a rating of 5 stars, more than 88% of patients must be adherent to each measure. These rates suggest a ceiling effect and a reduced ability to distinguish plan performance. In addition, concerns over the potential for plans to "game" these measures have been raised. The use of mail order services, 90-day prescription refill programs, and automatic refill reminders all improve the proportion of days covered measurement but may not reflect true adherence improvements. Given potential concerns associated with the use of the existing adherence measures, it may be time to consider their replacement. One option would be to adopt a broader inventory of chronic medications to measure adherence in the program and to rotate medication categories in the program each year. It might also be time to explore measuring patient adherence to all medications that a patient uses instead of the narrow focus on the 3 existing measures. DISCLOSURES: No funding supported the writing of this article. Farley has nothing to disclose. Urick reports consulting fees from Pharmacy Quality Solutions, unrelated to this work.