OBJECTIVES: While Medicare Part D research identifiable files have been available to academic researchers for some time, a new limited data set (LDS) containing Part D drug utilization and cost information is now available to both academic and non-academic researchers.  This study was undertaken to demonstrate the versatility of LDS in analyzing drug utilization and cost.  METHODS: Aged Medicare beneficiaries alive for all of 2008 with 12 months of Part A, B, and D coverage were selected.  The average number of prescription drug fills (30-day adjusted) and average costs per member per month (PMPM) were calculated overall, by demographics, and for selected chronic conditions.  Specific drug use was also examined for a chronic condition of interest. RESULTS: Overall, the average PMPM number of fills was 4.3 and the cost was $212, beneficiaries took 8.9 distinct medications, and mean cost per fill was $49.75.  Older beneficiaries filled more prescriptions per month (4.9 for ≥85 years vs. 3.9 for 65-74 years), but had lower mean costs per fill ($46.95 for ≥85 years vs. $51.61 for 65-74 years).  Females had higher PMPM fills (4.5 vs. 3.9) and costs ($220 vs. $198) compared to males.  Dual-eligible Medicare and Medicaid beneficiaries had approximately 1.5 times higher PMPM fills and costs compared to beneficiaries without any Part D subsidies.  PMPM fills and costs also vary with race.  Compared to the overall Medicare cohort, beneficiaries with the selected chronic conditions had higher PMPM fills and costs: diabetes (6.0, $303), Alzheimer’s (6.0, $358), depression (6.4, $357), and osteoporosis (4.8, $261).  Patterns of use and cost by demographics differed by condition compared to the overall cohort, except by dual eligible status. CONCLUSIONS: As demonstrated, the new Part D LDS data allows researchers to conduct utilization and cost studies using all and subsets of Medicare beneficiaries with selected chronic conditions.