Thameur, A., Ferchichi, A. and López-Carbonell, M. 2014. Involvement of abscisic acid metabolites and the oxidative status of barley genotypes in response to drought. Can. J. Plant Sci. 94: 1481-1490. Endogenous concentrations of free abscisic acid (ABA), abscisic acid glucosyl ester (ABAGE), phaseic acid (PA), dihydrophaseic acid (DPA) and 7'-hydroxy ABA (7'-OH ABA) were analysed by means of a LC-MS/MS system in five genotypes of barley (Hordeum vulgare L.) grown under well-watered and drought stress conditions. For this purpose a drought treatment was conducted using genotypes: ‘Ardahoui’, ‘Manel’, ‘Pakistan’, ‘Rihane’ and ‘Roho’. Our results show that free and conjugated ABA levels increased in all genotypes grown under water stress, except in Manel genotype, in which ABAGE levels were the lowest. In contrast, genotypes Ardhaoui and Roho showed the highest ABA and ABAGE levels. Nevertheless, drought Rihane plants showed the maximum ability to increase the endogenous ABA concentrations. PA, DPA and 7'-OH ABA increased also in all drought genotypes, especially in the leaves of Manel and Roho genotypes, while the highest ability to increase the endogenous PA content corresponded to genotypes Ardahoui and Pakistan. To evaluate the plant oxidative status, some antioxidant compounds were analysed. Under drought conditions, small changes in some of them were seen. Among the genotypes studied, Manel was the only one which did not show increases in malondialdehyde (MDA) and, in parallel, showed a decrease in ABAGE content. These results provide us valuable information and contribute to the knowledge of the different responses of these genotypes to drought stress.