The aim of this study was to evaluate the acute and chronic effects of two SSRIs (sertraline and fluoxetine) on anxiety by the elevated plus-maze test. Diazepam increased the time spent in open arms significantly whereas the anxiogenic m-chlorophenylpiperazine (m-CPP) decreased the time significantly. Acute sertraline (10 mg.kg-1) and fluoxetine (20 mg.kg-1) treatment significantly decreased the time spent in open arms. Acute fluoxetine (20 mg.kg-1) treatment also decreased the total number of enclosed arm entries. Seven days sertraline treatment decreased the time spent in open arms, whereas 14 days fluoxetine treatment increased the time spent in open arms. These results show that acute administration of SSRIs may produce anxiogenic effects in the elevated plus-maze test. © 2011, by Walter de Gruyter GmbH & Co. All rights reserved.