BACKGROUND: Prescription medication adherence is a known health related barrier for elderly patients, leading to insufficient disease control and negative health outcomes. Many barriers to prescription adherence have been identified in the literature, but it is unclear what barriers physicians feel most strongly inhibit adherence among patients enrolled in Medicare Advantage Part D (MAPD) plans. OBJECTIVES: To identify physician perceived barriers to medication adherence among MAPD patients. METHODS: A survey was developed and administered to primary care physicians (PCPs) contracted within a MAPD plan in Texas. Surveys were distributed during an all-PCP quarterly meeting to increase completion and return rates, and were collected prior to the meeting’s conclusion. A free response section was utilized for PCPs to indicate up to 3 of the top barriers to medication adherence that they feel impact their MAPD patients. Responses were categorized into 8 distinct groups (cost, side effects, formulary, lack of patient understanding, forgetfulness, transportation, dosage changes, and other). The “other” category encompassed cultural issues, language barriers, obtaining drugs out of the country or not using an insurance card, and problems at the pharmacy. RESULTS: A total of 210 PCPs (68%) across Texas completed and returned the survey. Cost was by far the most commonly identified barrier, reported by 77% of respondents. Patient understanding was also a big concern, identified by 53% of PCPs. Only 18% of PCPs indicated side effects (actual or potential) as a top barrier. Forgetfulness was cited by 22% of PCPs and transportation by 14%. Twenty percent of PCP responses fell within the “other” category defined above, while formulary (10%) and dosage change (2%) were the least frequently mentioned barriers. CONCLUSIONS: MAPD PCPs most frequently cite financial issues and lack of patient understanding as reasons for non-adherence in their patients.