In order to evaluate the potential involvement of immediate early genes in ischemic tolerance, we examined Fos- and Jun-related protein immunoreactivity in gerbil brain. Two minutes of preconditioning ischemia or sham operation was followed by 3-min ischemia 3 days later. The animals were sacrificed after 4 h to 7 days of survival. Fos immunoreactivity was seen in dentate hilar neurons 4 h after 3-min ischemia regardless of preconditioning. Jun immunoreactivity increased in dentate granule cells 4 h after 3-min ischemia without preconditioning. Prominent Jun immunoreactivity was induced in astrocytes in the CA1 region of the gerbils with ischemic tolerance. The result suggests that Jun may contribute to the ischemic tolerance by inducing changes in gen expression in astrocytes.