OIG has conducted numerous evaluations and audits of the manufacturer-reported pricing data used to calculate reimbursement amounts in Medicare Part B and rebates in Medicaid. One notable report examined the Accuracy of Drug Categorizations for Medicaid Rebates (OEI-03-08-00300). Brand-name drugs are generally subject to higher Medicaid rebates than generic drugs. Manufacturers are required to provide CMS with the brand/generic categorization for each of their drugs in conjunction with average manufacturer price (AMP) data. OIG found that in the fourth quarter of 2007, most manufacturer-reported brand/generic categorizations matched the categorizations in two national drug compendia. However, we identified eight drug codes from our sample for which manufacturers appeared to incorrectly classify brand-name products as generics, meaning that Medicaid may not have recouped all the money it was owed in rebates.