Changes in a test of memory performance were evaluated in 103 healthy young men after challenges with placebo and two different doses of intravenous diazepam (0.12 and 0.20 mg/kg). Both diazepam doses significantly impaired free recall in a dose-dependent manner. Within each dose challenge there was no significant correlation between the average serum diazepam or desmethyldiazepam levels and the average number of words recalled across the time points. The data expand our current understanding of the amnestic effects of benzodiazepines and suggest that patients abusing these drugs in large doses may develop profound degrees of memory impairment.