When benzodiazepines were introduced into clinical practice in the 1950s they were hailed as efficacious minor tranquillizers, largely devoid of unwanted side effects, in contrast to the barbiturates and similar drugs that they largely superseded. It was 30 years before the phenomenon of low-dose dependence on benzodiazepines was recognized. Benzodiazepine dependence differs from other psychotropic drug addictions because the benzodiazepines do not produce either euphoria or drug-seeking behaviour (except in those who are already addicted to other drugs). However, benzodiazepine use is associated in some individuals with a marked withdrawal (abstinence) syndrome that provides the best evidence of dependence. Just over half the people prescribed long-term benzodiazepines do not develop any sign of a withdrawal reaction (Fig. 1): this reflects factors including the type of benzodiazepine prescribed, the dosage and duration of treatment, as well as characteristics of the patient. Individuals with passive-dependent personalities appear to be more likely to experience withdrawal symptoms than other patients, although this remains a controversial issue. Therefore benzodiazepine use should follow certain guidelines, and if these are adhered to the benzodiazepines will continue to be valuable drugs in clinical practice.