The effects of chronic administration of the antidepressant drugs desipramine, nortryptiline and paroxetine (PAR) (10 mg/kg/day, 21 days) on changes in turning (circling) behavior and on norepinephrine (NE), dopamine (DA) and serotonin and their metabolites 3,4-dihydroxyphenylacetic acid and 5-hydroxyindole acetic acid (5-HIAA) in the medial prefrontal cortex (PFC), nucleus accumbens and striatum were evaluated in rats. All three drugs eliminated turning biases in right turning rats. All drugs increased DA concentrations in the PFC while PAR increased NE in the PFC and reduced 5-HIAA in all three structures. The results are discussed with reference to previous findings involving brain asymmetry in depression.