We have analyzed the allomonal secretions in 10 species of cockroaches belonging to seven genera and made a detailed reanalysis of these secretions in three other species previously studied. Forty-three products were identified (quinones, phenols, acids, ketones, aldehydes, lactones, hydrocarbons, alcohols and various products). In many cases, the function of these secretions is unknown. We were able to test in the laboratory and also in natural conditions the different products identified, and we were able to test the reactions of several cockroaches when attacked by natural predators (beetles, lizards, toads, and bats). InEurycotis decipiens, the secretion of the sternal glands has a strong deterrent effect on the predators. InEublaberus distanti, the secretion of the glands associated with the second abdominal spiracle acts as an alarm pheromone. In several species ofPeriplaneta, the function of the sternal secretions is unknown. The components of these allomonal secretions are discussed.