Testing procedures for identification of potential developmental neurotoxicants were evaluated using two prototypical developmental neurotoxicants, methylazoxymethanol (MAM) and methylmercury (MeHg). A number of endpoints in the testing strategy were sensitive to the effects of prenatal exposure to MAM (30 mg/kg on Gestation Day (GD) 15): (1) MAM caused reduced neonatal body weights but did not affect viability or postnatal survivorship; (2) measurement of total and regional brain weight and histological analysis showed that a number of regions, the cortex and hippocampus in particular, were affected by MAM exposure; (3) an assay for glial fibrillary acidic protein (GFAP) showed that the concentration of this protein was significantly increased in the cortex and hippocampus of treated offspring; (4) a T-maze delayed-alternation procedure indicated that MAM-treated pups were slower in the acquisition phase of the task relative to control pups; (5) motor activity testing revealed hyperactivity in treated offspring that persisted into adulthood; and (6) acoustic startle procedures revealed reduced startle amplitudes in preweanlings.