Behavioral effects of triethyltin were studied in rats living in Wahmann activity cages. Wheel running activity and food-reinforced lever pressing were recorded 23 hr/day from 4 rats. Triethyltin injections (4 mg/kg IP) produced large transient decreases in running, lever pressing, and daily water consumption, without affecting body weight. These measures recovered to pre-treatment levels within 1-2 days. After 4 weekly injections, wheel running was reduced in 2 rats, and increased in 1 rat, while lever pressing remained at baseline levels. Good correlation was noted between the extent of reductions in wheel running and lever pressing, and the extent of characteristic triethyltin-induced morphological lesions in the central and peripheral nervous system. Over the course of repeated treatments, several critical behaviors known to be sensitive to neurotoxicants can be continually monitored using automated testing apparatus. While further validation with more compounds is required, these results suggest that monitoring wheel running, food-reinforced lever pressing, and water consumption may be an inexpensive way to test for behavioral neurotoxicity using small numbers of animals.