252 Background: Patients with active cancer and multimorbidity (≥2 chronic conditions) are at increased risk of disease progression, hospitalization and death compared to patients without concomitant chronic conditions. Adherence to chronic medications is imperative in this patient population, but frequently declines after the initial cancer diagnosis. Reasons for this declining adherence are not well understood. We aimed to explore barriers and facilitators of chronic medication adherence among patients with multimorbidity and a recent cancer diagnosis. Methods: We conducted a qualitative study of patients with active solid organ cancer and multimorbidity receiving care at one academic health system in March-November 2023. We used purposive sampling to include balanced numbers of advanced (stage 3-4) and non-advanced (stage 1-2) cancers and perceived change in chronic medication adherence after cancer diagnosis (same/better vs worse). We asked participants to describe their perceptions of and experiences with balancing their cancer and non-cancer symptoms, medications, and medical appointments, as well as barriers to adherence and strategies used to help with adherence. We analyzed transcripts using thematic analysis. Results: We interviewed 20 patients aged ≥50 who had an average of 3 chronic conditions and took an average of 3 chronic medications. Three themes emerged. First, patients made decisions about which diseases, medications, and medical appointments to prioritize. Many focused their energy on their cancer treatment and appointments, putting management of their chronic conditions on pause. In contrast, patients with severe chronic conditions (e.g., heart failure, diabetes) prioritized avoiding hospitalizations for their chronic conditions so that they could continue their cancer treatment uninterrupted. Patients based their decisions on prior experience, as well as advice from caregivers and clinicians. Second, adherence fluctuated in response to drug side effects (e.g., nausea/vomiting), drug-disease interactions (e.g., weight loss reducing need for antihypertensives), drug-drug interactions, and conflicting recommendations from cancer and non-cancer care teams. Patients often most closely followed the recommendations of the clinician they viewed as being “in charge” of their care. Third, patients’ trust in caregivers, medical teams, and their own self-efficacy influenced their motivation to adhere to medications. Conclusions: Patients with cancer and multimorbidity must balance competing priorities, interactions between their cancer and non-cancer conditions, relationships with care teams and caregivers, and their own sense of self-efficacy. Further work is needed to devise strategies to address barriers to chronic medication adherence in this population and thus improve short- and long-term health outcomes.