In this double-blind, placebo-controlled study of 4 weeks of benzodiazepine treatment followed by 3 weeks of abrupt or gradual drug withdrawal, 16 patients whose benzodiazepine was withdrawn abruptly were worse (p less than .05) than 13 who had received placebo in terms of change in mean anxiety scores from the pretreatment level. The scores of seven patients (44%) whose benzodiazepine was withdrawn abruptly increased 10% or more on both the Hamilton Rating Scale for Anxiety and the Self Rating Symptom Scale. There were no cases of rebound anxiety in 14 patients whose benzodiazepine was withdrawn gradually; fewer cases of rebound anxiety were seen with a benzodiazepine that had a long half-life.