Road traffic accidents are a leading cause of mortality and morbidity, and their association with alcohol and drugs such as minor tranquillizers is well established (Seppala et al., 1979). There is also epidemiological evidence to associate the older, sedative antihistamines with motorcycle accidents (Skegg et al., 1979). Astemizole is a recently introduced H1-antagonist which, unlike older antihistamines, does not cause central nervous system sedation. The present study was designed to compare the effects of astemizole and chlorpheniramine, alone and in combination with alcohol, on an objective measure of psychomotor performance relating to car-driving ability.