The sex pheromone of the German cockroach, Blattella germanica, has been characterized as gentisyl quinone isovalerate. This cockroach is a major cause of allergic disease and serves as a mechanical vector of pathogens, making it one of the most important residential and food-associated pests worldwide. The sex pheromone-producing gland in adult females was identified in 1993, but thermal instability of the pheromone made characterization difficult. Now, using a new preparative gas chromatography approach coupled with electroantennographic detection, we have isolated and characterized the pheromone, which we term blattellaquinone, and confirmed the identification by chemical synthesis. The synthetic pheromone was active in behavioral assays and highly effective in field trapping tests, which suggest that it may provide a new tool in cockroach population detection, monitoring, and control.