The effects of a new 1,4 benzodiazepine hypnotic, loprazolam (1.0 mg) and alcohol (0.7 g/kg body weight) were investigated over a 15 h period in eight healthy male medical students, in a placebo controlled balanced design. Loprazolam when given alone impaired performance on a manual dexterity task, on a test of mental arithmetic, on a tracking task and it impaired memory as judged by the name and address memory test. Given alone, alcohol impaired performance on the simple reaction time task and on the tracking task. Performance on the memory test and choice reaction time test actually improved. No evidence was found suggesting a potentiation of effect when loprazolam and alcohol were given together. However, (a) on the manual dexterity task the alcohol, having no effect on its own, alleviated the loprazolam-induced impairment. (b) In the tracking task both alcohol and loprazolam impaired performance when given alone but not when given together. (c) The memory test was impaired by loprazolam, improved by alcohol and the effect of the combination is the expected sum of the two effects. Similarly for the arithmetic task the effect of the combination of the alcohol and loprazolam effects is the expected sum of the independent effects. The bulk of the evidence on the interaction suggests that alcohol mitigates the effects of loprazolam. In no sense could the drug be said to be having a sobering influence.