Foetal rat brain aggregation cultures were exposed to a single episode of anoxia and hypoglycaemia for 30 min. Lactate dehydrogenase specific activity was estimated in the culture medium after ischaemia as a marker of lost cell integrity. Release of lactate dehydrogenase was most prominent during the first 24 hr period after the ischaemic damage, then it gradually declined. Immediately after ischaemic exposure, the cultures were treated with different concentrations of L-deprenyl or tolcapone. Significantly lower amounts of lactate dehydrogenase leaked into the culture medium during the first 24 hr after the ischaemic episode in cultures treated with deprenyl or tolcapone (1-100 nM). These results suggest that deprenyl and tolcapone may reduce cell damage after ischaemia, at doses causing enzyme inhibition.