The aim of this study was to determine the modulation of anxiolytic effect of diazepam by gend-er and hormonal cycle in rats. For this, 160 rats (32 male and 128 female) were divided per sex and female estrous cycle phase (estrus, diestrus, metaestrus and proestrus) and diazepam dose (0,0, 0,5, 1,0 and 2,0 mg/kg) in 20 groups (n = 8 each). The females were accompanied in their estrous cycle, and those with irregular cycles were discarded. Animals from all groups were submitted, 25 min after drug administration, to one session on the elevated T maze, a animal behavioral test to study of panic and anxiety. The test consisted of three avoidance trials and one escape trial, separated of each other by a 30 s interval, during which the animals were isolated in individual cages. The avoidance trials began with the animal being placed at the end of the maze's enclosed arm. The time necessary for the animal to leave the central square was consi-dered as the response's latency. The trails that exceeded 300 s were considered as failures. The results showed differences between the groups, with a modulation of the cycle and gender on the anxiolytic effects of the diazepam, in a dose and phase dependent model.