Whole plants and detached leaves ofCymbopogon martiniicultivars were exposed to water stress for growth and essential oil metabolism studies. The cultivars differed considerably in their response to stress. Plant growth, oil yield, relative water content and water potential decreased while PEP carboxylase activity (PEPC; EC 4.1.1.31) increased in cultivars ‘Tripta,’ Trishna' and ‘PRC1’ grown for 120 days under stress. Similarly in excised leaves of cultivars RRL(B)-77, RRL(B)-69, IW-31245E and RRL(B)-77E water potential and relative water content decreased while proline level increased due to water stress. PEP carboxylase activity was enhanced in all the cultivars except in RRL(B)-69. On inducing water stress in plants or in detached leaves, level of essential oil and geraniol decreased, increased or showed no change in the different genotypes.