There has been a surge of interest over the past several years in the use of neurochemical endpoints to contribute to our understanding of the mechanism of action of neurotoxicants. In our present presentation, two biogenic amine systems were selected as examples of biomarkers for neurotoxicity. To investigate these neurochemical endpoints, two prototype neurotoxicants were evaluated in experimental animals. One agent, reserpine, was used to assess developmental neurotoxicity and administered prenatally, while the other, MDMA, was used in the adult animal. The neurochemical biomarkers measured were dopamine, serotonin, and their metabolite (DOPAC and 5-HIAA) concentrations by HPLC/EC and dopamine receptor binding by radioligand receptor techniques. A review of the background, experimental design, and results are presented in this article. Our findings indicate that components of the biogenic amine systems can be used as sensitive neurochemical biomarkers of neurotoxicity. These neurochemical biomarkers There has been a surge of interest over the past several years in the use of neurochemical endpoints to contribute to our understanding of the mechanism of action of neurotoxicants. In our present presentation, two biogenic amine systems were selected as examples of biomarkers for neurotoxicity. To investigate these neurochemical endpoints, two prototype neurotoxicants were evaluated in experimental animals. one agent, reserpine, was used to assess developmental neurotoxicity and administered prenatally, while the other, MDMA, was used in the adult animal. The neurochemical biomarkers measured were dopamine, serotonin , and their metabolite (DOPAC and 5-HIAA) concentrations by HPLC / EC and dopamine receptor binding by radioligand receptor techniques. A review of the background, experimental design, and results are presented in this article. Our findings indicate that components of the biogenic amine systems can be used as sensitive neurochemical biomarkers of neurotoxicity. These neuroch emical biomarkers