Aims  To re‐examine various aspects of the benzodiazepines (BZDs), widely prescribed for 50 years, mainly to treat anxiety and insomnia. It is a descriptive review based on the Okey Lecture delivered at the Institute of Psychiatry, King's College London, in November 2010.

Methods  A search of the literature was carried out in the Medline, Embase and Cochrane Collaboration databases, using the codeword ‘benzodiazepine(s)’, alone and in conjunction with various terms such as ‘dependence’, ‘abuse’, etc. Further hand‐searches were made based on the reference lists of key papers. As 60 000 references were found, this review is not exhaustive. It concentrates on the adverse effects, dependence and abuse.

Results  Almost from their introduction the BZDs have been controversial, with polarized opinions, advocates pointing out their efficacy, tolerability and patient acceptability, opponents deprecating their adverse effects, dependence and abuse liability. More recently, the advent of alternative and usually safer medications has opened up the debate. The review noted a series of adverse effects that continued to cause concern, such as cognitive and psychomotor impairment. In addition, dependence and abuse remain as serious problems. Despite warnings and guidelines, usage of these drugs remains at a high level. The limitations in their use both as choice of therapy and with respect to conservative dosage and duration of use are highlighted. The distinction between low‐dose ‘iatrogenic’ dependence and high‐dose abuse/misuse is emphasized.

Conclusions  The practical problems with the benzodiazepines have persisted for 50 years, but have been ignored by many practitioners and almost all official bodies. The risk–benefit ratio of the benzodiazepines remains positive in most patients in the short term (2–4 weeks) but is unestablished beyond that time, due mainly to the difficulty in preventing short‐term use from extending indefinitely with the risk of dependence. Other research issues include the possibility of long‐term brain changes and evaluating the role of the benzodiazepine antagonist, flumazenil, in aiding withdrawal.