Thiobencarb (S-(4-chlorobenzyl)-N,N-diethyl thiol carbamate), a dithiocarbamate herbicide, was found to cause neuronal dysfunction in adult and neonate albino rats. In general, organocarbamates exert their action by inhibiting acetylcholinesterase (AChE) activity. Thiobencarb inhibited both acetylcholinesterase and adenosine triphosphatase (ATPase) activities in rat brain. Withdrawal of thiobencarb treatment resulted in the recovery of AChE activity to a normal level, whereas there was no recovery of Na(+)-K(+)-ATPase activity in either neonate or adult rat brains. The results suggest that neuronal dysfunction caused by thiobencarb is mainly due to the inhibition of ATPase activity rather than to the inhibition of AChE activity.