The main actions of benzodiazepines (hypnotic, anxiolytic, anticonvulsant, myorelaxant and amnesic) confer a therapeutic value in a wide range of conditions. Rational use requires consideration of the large differences in potency and elimination rates between different benzodiazepines, as well as the requirements of individual patients. As hypnotics, benzodiazepines are mainly indicated for transient or short term insomnia, for which prescriptions should if possible be limited to a few days, occasional or intermittent use, or courses not exceeding 2 weeks. Temazepam, loprazolam and lormetazepam, which have a medium duration of action are suitable. Diazepam is also effective in single or intermittent dosage. Potent, short-acting benzodiazepines such as triazolam appear to carry greater risks of adverse effects. As anxiolytics, benzodiazepines should generally be used in conjunction with other measures (psychological treatments, antidepressants, other drugs) although such measures have a slower onset of action. Indications for benzodiazepines include acute stress reactions, episodic anxiety, fluctuations in generalised anxiety, and as initial treatment for severe panic and agoraphobia. Diazepam is usually the drug of choice, given in single doses, very short (1 to 7 days) or short (2 to 4 weeks) courses, and only rarely for longer term treatment. Alprazolam has been widely used, particularly in the US, but is not recommended in the UK, especially for long term use. Benzodiazepines also have uses in epilepsy (diazepam, clonazepam, clobazam), anaesthesia (midazolam), some motor disorders and occasionally in acute psychoses. The major clinical advantages of benzodiazepines are high efficacy, rapid onset of action and low toxicity. Adverse effects include psychomotor impairment, especially in the elderly, and occasionally paradoxical excitement. With long term use, tolerance, dependence and withdrawal effects can become major disadvantages. Unwanted effects can largely be prevented by keeping dosages minimal and courses short (ideally 4 weeks maximum), and by careful patient selection. Long term prescription is occasionally required for certain patients.