The are few reports on the relationship between elevated plus-maze and effects of maintenance conditions in the days prior to the test.Previously, we have demonstrated that being forcibly in total dark or in light for four days does not alter exploratory behavior in the plus-maze.The present study aimed at recording illumination level preferences in rats using a box with light and dark compartments (or another with two light compartments) and the behavioral effect of this choice on the plus-maze.The rats allowed to express their preference to remain in one particular level of illumination tended to stay initially in the dark compartment and gradually preferred to remain in the light compartment.When tested in the elevated plus-maze there were no effects in comparison to controls kept in commercial cages.