Free recall of words has been extensively used in psychopharmacology to assess the effects of CNS-active drugs on memory functions. However, there is a relative lack of information on the impact of word frequency on the subsequent recall of words following the administration of psychoactive drugs. The present double-blind, placebo-controlled, repeated-measures experiment used lorazepam and alcohol to test the effects of word frequency on immediate and delayed word recall in 24 healthy volunteers. One half of the words contained in the lists had a high frequency (HF) of occurrence and the remainder were of low frequency (LF). The results showed that LF words were more sensitive to memory impairment than HF words. However, the more accurate recall of HF words (with respect to LF words) was eliminated when a combination of lorazepam with alcohol was administered. These findings indicate that word frequency has a significant impact on memory and, as such, is a factor to be taken into account when using memory recall tasks to assess the effects of psychoactive drugs on memory.