Pregnant CBA mice were exposed to aluminium sulfate at a dose of 200 mg/kg body wt injected intraperitoneally during Days 10 to 13 of gestation. We used a variety of ethological measures, which have been shown to be sensitive indicators of toxicants, to assess effects on the mother and the behavioral development of pups. Prenatal aluminium resulted in a reduction in the rate of ultrasonic calling by pups accompanied by a shift in the timing of peak calling; treated pups exhibited decreased growth and delays in neurobehavioral development. The treatment received by a pup's foster mother was also found to influence development. We recommend ultrasonic calling as a sensitive measure in studies of behavioral teratogenicity.