The efficacy of diazepam for controlling phobic avoidance behavior and phobic anxiety and the potential usefulness of the behavioral approach measure for screening new antianxiety drugs was investigated in a double-blind study. The distance from the phobic object beyond which the subject would not approach and a rating of subjective anxiety at closest approach were made in 14 phobic patients immediately before and again 2 hr after 10-mg oral diazepam or placebo. Behavioral approach to the object was increased and subjective anxiety was decreased by diazepam as compared to placebo. The method appeared useful for early clinical screening of new drugs because it discriminated drug from placebo in a single short session using small groups and because it employed a more objective dependent measure than self-report of subjective feeling states.