The effects of the 5-HT2A/2C receptor antagonist, ketanserin, on lordosis behavior were examined in hormonally primed, ovariectomized Fischer and Sprague-Dawley females. Rats were primed with 0.067μg/g body weight estradiol benzoate and 3.33μg/g body weight progesterone. After a pretest for sexual behavior, rats were injected with 0.416 to 10mg/kg ketanserin. In both strains, lordosis behavior, lordosis quality, and proceptivity were significantly reduced by ketanserin. There was modest evidence of a strain difference with Sprague-Dawley females slightly more sensitive to ketanserin. In a second experiment, the effects of 10mg/kg fluoxetine, 1mg/kg ketanserin, and their combination were examined to determine if the two drugs would have additive effects on sexual behavior. There was no evidence that the drugs were additive in their effect and the strains did not differ in their response to the combined treatment. These findings are discussed in relation to prior evidence for strain differences in the sexual behavioral response to fluoxetine and to a receptor agonist acting preferentially at 5-HT1A receptors.