Benzquinamide was compared to chlordiazepoxide and placebo in a triple-blind study. Doses within the clinical range were used. The subjective experiences with the respective preparations as well as autonomic changes during experimental stress (under the influence of the respective preparations) were recorded. Benzquinamide did not show any more positive subjective effects than placebo and produced mainly unpleasant effects. Chlordiazep-oxide differed favourably from both placebo and benzquinamide and showed several significant positive effects indicating well-being and friendliness, while it had remarkably few disagreeable effects. The autonomic findings, although few, in all respects supported the subjectively reported effects. Chlordiazepoxide showed better abilities than benzquinamide to counteract as well autonomic as emotional effects of stress. Chlordiazepoxide in this and a previous study was found to possess valuable properties as a tranquilizer, while benzquinamide did not at all show promising properties.