The effects of viloxazine on the flexor reflex of the hind limb of the spinal rat and the blood pressure in the pithed rat were studied. Viloxazine (1--16 mg/kg) stimulated the hind limb flexor reflex in the dose-dependent manner. This effect of viloxazine was inhibited by serotonin receptor blockers, cyproheptadine, danitracen and metergoline, and by serotonin uptake blocking agents imipramine and clomipramine. H22/54, an inhibitor of serotonin synthesis, was much less active in this respect. Desipramine, a noradrenaline uptake inhibitor, had no effect on the stimulatory action of viloxazine. Viloxazine (similarly as serotonin) elevated blood pressure in the pithed rat. This action of viloxazine was abolished by cyproheptadine but potentiated by pargyline, an inhibitor of MAO. It is suggested that viloxazine may facilitate the serotonergic transmission in the central nervous system.