To evaluate the impact of transitioning from Medicaid to Medicare Part D drug coverage on the use of noncancer treatments among dual enrollees with cancer. We leveraged a representative 5% national sample of all fee-for-service dual enrollees in the United States (2004-2007) to evaluate the impact of the removal of caps on the number of reimbursable prescriptions per month (drug caps) under Part D on 1) prevalence and 2) average days’ supply dispensed for antidepressants, antihypertensives, and lipid-lowering agents overall and by race (white and black). The removal of drug caps was associated with increased use of lipid-lowering medications (days’ supply 3.63; 95% confidence interval [CI] 1.57-5.70). Among blacks in capped states, we observed increased use of lipid-lowering therapy (any use 0.08 percentage points; 95% CI 0.05-0.10; and days’ supply 4.01; 95% CI 2.92-5.09) and antidepressants (days’ supply 2.20; 95% CI 0.61-3.78) and increasing trends in antihypertensive use (any use 0.01 percentage points; 95% CI 0.004-0.01; and days’ supply 1.83; 95% CI 1.25-2.41). The white-black gap in the use of lipid-lowering medications was immediately reduced (-0.09 percentage points; 95% CI -0.15 to -0.04). We also observed a reversal in trends toward widening white-black differences in antihypertensive use (level -0.08 percentage points; 95% CI -0.12 to -0.05; and trend -0.01 percentage points; 95% CI -0.02 to -0.01) and antidepressant use (-0.004 percentage points; 95% CI -0.01 to -0.0004). Our findings suggest that the removal of drug caps under Part D had a modest impact on the treatment of hypercholesterolemia overall and may have reduced white-black gaps in the use of lipid-lowering and antidepressant therapies.