This is a practical book, for use in the clinic, ward or surgery. It advises when and how to use medication to help people with psychological disturbances. Drug prescriptions are described in the context of the general management of the individual patient. Where possible, treatments are based on established evidence; otherwise they represent our own experience and what we teach as good practice. It is not necessarily the only successful way of doing things, but one we can recommend in the present state of knowledge. It is based on our belief that taking pains over the choice, introduction and dose schedule of drugs results in better therapeutic results and fewer side-effects and reduced toxicity. We have introduced a particular method to display evidence resulting from randomised controlled trials, using the concept of 'number needed to trat'; we hope that this proves a helpful and user-friendly approach. We have also included a large number of references for further reading. In the past, many psychiatrists have been prepared to take great trouble over their psychotherapeutic handling of patients, but used drugs in a less thoughtful way. They have sometimes been frightened of proper doses, or combinations, or persisting for long enough with medical treatment. We believe that psychological treatment must often be combined with drug treatment, in a balanced way, to relieve and to cure. The book is divided into three sections. The first is a general introduction to the social and neurobiological background and to psychological and social factors to be borne in mind in good prescribing. It can be read as a whole, or in parts, at any time. Brain structure, neurotransmitters and receptors are described, focusing on aspects that seem of most relevance to the drugs in current use. The second section is a series of essays on the role of drugs in different psychiatric conditions and the third an account of the drugs currently available in Britain for psychiatric treatment. These two sections work together, the former describing the factors affecting the choice of particular drugs for the condition and the latter giving more detail about the mechanisms of action of the drugs and their side-effects. In everday use one may dip into the book by looking up an individual drug through the index of trade and approved names, or use the symptom index to see what the book says about treatment of a particular symptom or syndrome. One can also take the patient's diagnosis, read the appropriate part of the management chapter and look up the mentioned drugs in the third section. While, simply for information, we give the names of all available drugs, we do not give details about all of them. In some groups we give one at length that we regard as typical of the group and well established, and follow it with shorter entries on others of the same group that we regard as useful. When describing side-effects we try to name the commonest and most important first, the lesser ones later;