Recently the federal government has increased efforts to stop the flow of drugs into the United States. However, the replacement cost of drugs seized at the border is small in comparison to the replacement cost of drugs seized at some point closer to the consumer. The use of unweighted seizure quantities as the measure of drug enforcement effectiveness, therefore, overstates the impact of federal agencies. This Note suggests that a more appropriate measure of drug enforcement effectiveness is the cost of replacing the seized drugs. It examines the largest single component of the federal drug enforcement effort, the interdiction program, with particular emphasis on its effect on cocaine use in the United States. The author presents an analytical framework in which the argument for using price levels as a measure of the effectiveness of drug enforcement is developed. He then presents some data on the scale and effect of the drug interdiction program. Finally, he employs a recently developed simulation model to illustrate how increased interdiction would have only a slight impact on the total domestic consumption of cocaine.