The effect of serotoninergic activation on gonadotropin and prolactin release were analysed in 16-day-old intact female rats. In the first experiment, females were decapitated 30 min after i.p. administration of 100 mg/kg of 5-hydroxytryptophan (5-HTP) or vehicle; in the second experiment the rats were decapitated 15 and 30 min after i.p. injection of vehicle or some doses (0.1, 1 and 10 mg/kg) of 8-hydroxy-2-(di-n-propylamino) tetralin (8-OH-DPAT), a selective agonist of the serotonin (5-HT)1A receptors. We found that: 1) serum follicle-stimulating hormone (FSH), luteinizing-hormone (LH) and prolactin concentrations increased after 5-HTP administration; 2) serum LH and prolactin concentrations and pituitary prolactin content increased after administration of 8-OH-DPAT. Our results indicate that in prepubertal rats, activation of serotoninergic system stimulated gonadotropin and prolactin release, and that 5-HT1A receptors are involved in this effect. In addition, the simultaneous increase in serum and pituitary prolactin content suggests that 8-OH-DPAT enhances prolactin synthesis.