International air travel has long been considered a significant means of moving pest organisms. Passengers may carry pests (e.g., snails, weed seeds), or items that are infested with pests (e.g., fruits or vegetables). Our objective was to use data collected by the U.S. federal government to estimate plant quarantine material (QM) approach rates (the percentage of sampling units containing QMs) and the annual number of plant QMs entering the United States in airline passenger baggage. We concluded that the pest risk associated with passenger baggage may be considerable. In the United States, the risk from international airline passenger baggage can be mainly attributed to travelers who are visiting family or friends (about one third of the travelers). Several Caribbean countries were among the 25 countries of passenger origin with the highest plant QM approach rates.