Zolpidem, a new imidazo-pyridine hypnotic, acts like a benzodiazepine. Because of its short half-life, zolpidem plays a special role in the group of drugs suitable for anesthesiological premedication because of its sedative and anxiolytic effects. The study compared preanesthesiological treatment by zolpidem and phenobarbital in combination with promethazine in a clinical setting. In a double-blind randomized design, 304 patients awaiting different kinds of surgery were studied. For the assessment of emotional states, a multidimensional rating scale was administered. The study showed differing effects of zolpidem and phenobarbital, which could be demonstrated in the scales ‘irritation’, ‘vulnerability’, and ‘aggression’ and could therefore represent in domain hostility. In most of the other scales there were similar effects of phenobarbital and zolpidem. Assuming that phenobarbital is a potent sedative, the reported results confirm the results found by other authors, that zolpidem also acts as a sedative. The reported results describe promethazine as selectively deactivating. These results are in agreement with the findings of an experimental study which tested the acute effects of stress under p