The observation in mice of antinociceptive activity of the EO from Cymbopogon citratus at the dose of 25 mg/kg (Viana et al., 2000) and an anticonvulsant effect of the EO from Cymbopogon winterianus (Quintans-Júnior et al., 2008) at doses below 400 mg/kg encouraged us to evaluate the anxiolytic activity of lower doses of the EO from Cymbopogon citratus. This approach showed positive results in anxiety-related parameters in the LDB, in which EO was active at 10 mg/kg. The biphasic dose– response (U-shaped) curve observed in the experiment is similar to the curves extensively studied by Calabrese and Baldwin (2003). This is an example of the dose– response relation noticeable in the field of neuroscience, especially in pre-clinical screening tests for central nervous system therapeutic agents (Carvalho-Freitas and Costa, 2002; Calabrese, 2008)