OBJECTIVES: Nonadherence to hormonal therapy is known to impact health outcomes in patients with breast cancer. We measured nonadherence to aromatase inhibitors using a novel, clinic-based patient-reporting system. METHODS: Patients of The West Cancer Center (Memphis, TN) were surveyed in the clinic prior to a scheduled appointment using the Patient Care Monitor system, a tablet-based, patient-reported outcomes platform. Adults diagnosed with breast cancer and prescribed an aromatase inhibitor were eligible to participate. The survey included 30 questions and used three established instruments, including the Morisky Medication Adherence Scale and Medication Adherence Reasons Scale. The survey polled patients on their adherence to aromatase inhibitors, reasons for nonadherence, and health literacy.  RESULTS: Over the course of 45 days, 3016 patients were self-screened for eligibility and interest; 1105 indicated interest; and 110 patients were fully eligible and completed the survey. Respondents were well-distributed by medication: anastrazole (42.2%), exemestane (33.9%), and letrozole (23.9%). Most patients (82.6%) reported being fully adherent (missed 0 days) in the past week; however, only 67.9% reported high adherence (score = 4) according to the Morisky Medication Adherence Scale (Spearman rho= -0.457, p-value<0.0001). Mean adherence values or days missed did not differ significantly by medication or health literacy level. Among patients who reported missing at least one day in the previous week, the most often cited reasons were: simply missing the dose (44.4%), having problems forgetting things (38.9%), and concerns about side effects (33.3%). CONCLUSIONS: Adherence to hormonal therapy remains suboptimal and determining reasons for nonadherence prior to scheduled visits may assist providers in guiding patients. Moreover, the clinic’s Patient Care Monitor system is a novel patient engagement platform to collect patient-reported adherence data outside of the medical encounter, and may be leveraged to provide adherence and toxicity information to the healthcare team in real time.