Lorazepam, a new benzodiazepine, has recently been under investigation as a parenterally administered premedicants. These studies, in man, have shown not only that subjects experienced sedation and hypnosis, but also that many experienced a marked lack of recall.In a previous study, we were able to demonstrate significant impairment of human performance, specifically hand-eye coordination, produced by oral administration of Δ9tetra-hydrocamabiinol.2Others have shown the visual tracking task to be sensitie to the effects of drugs such as alcohol and smoked marijmana cigarettes.3–7Therefore, this investigation was done to study the effects of lorazepam and pentobarbital on visual tracking and to determine whether they affected it. We believed this would be important because there is evidence that performance on cirtical tracking tasks correlates with skills used in driving, flying, boating and industrial work.