OBJECTIVES: 1) To describe how many Medicare Part D enrolled seniors without Low Income Subsidy (LIS) reached the doughnut hole (coverage gap) in 2007, when they reached the doughnut hole, and how long they stayed in it. 2) To compare drug use and expenditures between Part D enrolled seniors without LIS who reached the doughnut hole and those who did not. METHODS: A retrospective, descriptive study design was used for the study. Data were extracted from the claims database of a supermarket pharmacy chain in Virginia. Study population was identified using the following selection criteria: age 65 as of January 1, 2007, at least one prescription fill at the participating pharmacy chain between January 1 to December 31, 2007, enrollment in a Medicare Part D plan throughout 2007, and no LIS in 2007. Whether or not a person had reached doughnut hole was determined at the patient-level for each month based on the cumulative total drug spending in that month. Descriptive statistics were used for the first objective. T-tests were used to compare seniors who reached the doughnut hole and those that did not. RESULTS: Just below 14% of Part D enrolled seniors without LIS reached the doughnut hole in 2007, of which, about 15% reached the catastrophic coverage. Part D enrolled seniors who reached the doughnut hole had significantly higher drug use, expenditures, and proportion of brand medication fills as compared to seniors that did not reach the doughnut hole. CONCLUSIONS: A relatively low proportion, but vulnerable population of Part D enrolled seniors without LIS reached the doughnut hole in 2007. Seniors who reached the doughnut hole had a significantly lower proportion of generic medication fills, suggesting that there is an opportunity to delay or even avoid the doughnut hole for some seniors by switching to lower-cost generics.