In a double-blind, six-way crossover study the effects on psychomotor performance and memory of single doses of Ro 41-3696 (1, 3, 5 and 10 mg), a novel non-benzodiazepine partial agonist at the benzodiazepine receptor, zolpidem (10 mg) and placebo were compared after night-time administration to 12 healthy young male subjects. Psychomotor performance tests (tracking and attention as part of a standardized task battery) were conducted just before and at 1.5 and 8 h after drug intake. The memory test consisted of the recall of a list of 15 words at 8 h after drug intake which had been learned at 1.5 h after intake. At 1.5 h after drug intake 10 mg zolpidem induced markedly larger psychomotor effects than any dose of Ro 41-3696. The effects of 5 and 10 mg Ro 41-3696 and zolpidem were significantly greater than those of placebo (P < 0.05). The following morning, 8 h after drug intake, the slight residual effects of 5 and 10 mg Ro 41-3696 were statistically significantly greater than placebo, whereas zolpidem effects did not differ from placebo. The results of the memory test showed that learning as well as recall were most clearly impaired by zolpidem. An influence of Ro 41-3696 on these variables was not observed for doses up to 5 mg. In conclusion, Ro 41-3696 at all doses tested induced less effects on psychomotor performance and memory than 10 mg zolpidem at 1.5 h after intake. However, the effects of Ro 41-3696 appeared to be of longer duration.