The benefits and risks of the benzodiazepines when used to treat generalised anxiety disorder, panic disorder and insomnia are important considerations. In discussing these parameters a distinction must be drawn between short term (of up to 28 days) and long term use.Benzodiazepine anxiolytics and hypnotics have undoubted efficacy, although it can be difficult to distinguish between a substantial nonspecific (placebo) effect and true pharmacodynamic drug effects. Response to benzodiazepines is prompt. However, in the long term, efficacy wanes and becomes difficult to disentangle from the suppression of rebound or withdrawal.The risks of benzodiazepines are well known, and comprise those associated with drug use and those that occur following discontinuation. Benzodiazepines have effects on psychological function, such as cognition and memory, and psychomotor performance. This translates into some interference with real-life functioning. Tolerance occurs to many but not all of these effects. Benzodiazepines have few effects on physical function, few drug interactions and are fairly safe in overdose.On discontinuation after short term use, some rebound of the disorder for which the agents were prescribed may occur. After long term use, up to a third of patients will show a characteristic and clinically troublesome withdrawal syndrome.Anxiety, panic and insomnia are unpleasant conditions that, especially in their severest forms, are associated with appreciable mortality. Alternative treatments to benzodiazepines are being developed, but are most efficacious in milder conditions. Therefore, the use of benzodiazepines can be justified in the short term management of anxiety, panic disorder and insomnia. However, in the long term, the risks of these agents probably outweigh their benefits.