Since January 1992, all benzodiazepines have been classified as dangerous drugs under the Dangerous Drugs Ordinance in Hong Kong. This legislative provision requires medical practitioners and pharmacists to keep a detailed record of their prescriptions of benzodiazepines The present study looks at the impact of the provision on prescribing trends in the Hong Kong population and in a general psychiatric clinic. A comparison of the 1991 (baseline level) and 1994 figures reveals a 50% and a 10% reduction in the average yearly number of benzodiazepine prescriptions per person in the Hong Kong population and in the general psychiatric clinic, respectively. In particular, triazolam prescriptions had the greatest reduction. The findings are discussed in light of the possible changes of prescribing practice by medical practitioners after the new legislative provision came into effect.