OBJECTIVES: Lenalidomide is a disease-modifying oral medication approved for the treatment of multiple myeloma as well as other myelodysplastic syndromes. A CarePak^® is a drug regimen packaging tool that simplifies complex drug regimens for patients. This tool is frequently used for patients receiving drug regimens containing lenalidomide. The impact of this tool on duration of therapy has previously not been studied. METHODS: This study was a retrospective review of pharmacy claims data.  Eligible patients included those who filled a lenalidomide prescription more than once, did not have a gap between fills longer than 60 days. Patients receiving a CarePak^® must have received one with all of their dispenses and for at least 6 consecutive months. Duration of therapy was calculated as the time between a patient’s first and last fill, including the most recent day’s supply. RESULTS: A random sample of patients filling between 2009 and 2014 was used for this analysis. To assess differences in duration of therapy, 225 patients receiving CarePaks^® and 225 patients not receiving CarePaks^® were identified. Duration of therapy for patients utilizing CarePaks^® and for patients not utilizing CarePaks^® was10.5 months and 8.4 months respectively, representing a difference of 2.1 months (p = 0.001). CONCLUSIONS: The use of CarePaks^® significantly improved duration of therapy in patients receiving lenalidomide compared to patients not using CarePaks^®