Class of 2016 Abstract / Objectives: Patient medication adherence is a basic requirement for treating chronic myelogenous leukemia (CML) with oral tyrosine kinase inhibitors (TKIs). When imatinib adherence rates are less than 80 or 90 percent, major and complete molecular responses, respectively, do not happen. The purpose of this study was to determine the effect of a real-time medication monitoring (RTMM) reminder system adherence program on the medication possession ratio (MPR). Methods: This analytic study was a retrospective cohort study and used data extracted from chart reviews for patients who received services from 2011 to 2015. It was approved by the Institutional Review Board. The study consisted of an intervention group and a control group (50 patients each). MPRs, demographic, descriptive, and categorical variables were summarized using means, standard deviations (SD), and frequencies/percentages. Results: The study population consisted of adult patients (mean age=62.2, SD=2.7, 50% male) treated by Avella Specialty Pharmacy who received imatinib or nilotinib as treatment for CML, gastrointestinal stromal tumors (GIST), or a similar positive Philadelphia chromosome cancer. Only 4% of patients in the intervention group had an < 85% MPR, compared to 46% in the control group (p < 0.001). Conclusions: In those patients who had an MPR of ≥ 85%, the difference between the groups was statistically significant. As past studies have shown, adherence rates greater than 90% have a higher likelihood of a major or complete molecular response and a greatly reduced risk of disease progression.