This series of studies revealed that a 2.5-mg dose of oxythiamine administered over 2 days yielded memory deficits from 10 min following passive avoidance learning. This result existed in association with slowing of righting reflex. Administration of thiamine reversed the memory deficit and the slowing of the righting reflex. A combination of oxythiamine and peripheral alcohol administration also resulted in memory deficits appearing from 10 min after training; however, in contrast to the effect of thiamine deficiency alone, the deficits induced by thiamine deficiency in association with acute administration of alcohol could not be reversed by thiamine resupplementation. The combination of alcohol and oxythiamine also slowed the righting reflex, but higher doses of thiamine also were unable to ameliorate the memory deficit caused by a combination of oxythiamine and alcohol; however, the slowing of righting reflex was reversed. The results suggest that preexistent thiamine deficiency may make the subject susceptible to the neurotoxicological effects of alcohol on memory function.