Medication non-adherence is commonly seen among patients with cardiovascular disease. However, failure to fill prescriptions, a type of medication non-adherence, is rarely studied among these patients. Failure to fill prescriptions, also known as primary medication non-adherence (PMN), can lead to progression of disease condition and adverse outcomes which can ultimately increase healthcare costs. Therefore, it is important for patients, especially who are newly diagnosed with cardiovascular disease to fill their prescriptions. The incidence of cardiovascular disease is higher in elderly population. Hence, elderly population is susceptible to PMN, but little is known about the extent of PMN for this population and its impact on health service utilization. Recent healthcare reform emphasizes on giving high quality care to elderly patients with chronic conditions such as cardiovascular disease. Since medication adherence is a quality measure for healthcare service received by this population, efforts should be made in identifying ways to improve PMN. Hence, the objective of this study is to measure the rate of PMN, assess reasons and factors that are associated with PMN and compare health service utilization behavior between adherent and non-adherent Medicare covered elderly population with newly diagnosed cardiovascular disease. This was a cross-sectional cohort study of Medicare beneficiaries with newly diagnosed cardiovascular disease using Medicare Current beneficiaries Survey (MCBS) files from 2002 to 2006. Andersen's model of health service utilization was used as a theoretical framework to define factors that may be associated with PMN. Seven thousand five hundred and forty-two Medicare beneficiaries were newly diagnosed with cardiovascular disease from years 2002 to 2006. Out of these, 334 patients did not fill prescriptions which represented 4.43% of the cohort under study. Female gender (OR 0.682, 95% CI 0.522-0.890), lower patient satisfaction score on ov (open full item for complete abstract)