The potential role of psychopharmacology in suicide prevention is often minimised. This may to some extent reflect that few medication trials have specifically focussed on prevention of suicidal behaviour--indeed this outcome is often not reported in trials. However, there is reasonably strong evidence that lithium may reduce risk of suicide, the postulated mechanism being a specific effect on aggression. Evidence is lacking with regard to any protective effect of other mood stabilizers. Clozapine may reduce suicidal behaviour in patients with schizophrenia, with reduction of affective symptoms being a possible explanation. The role of antidepressants in relation to suicide risk is highly controversial, especially in children and adolescents. It is unclear whether minor tranquillizers or hypnotics can assist in suicide prevention, although they can reduce the anxiety symptoms that may occur during initial treatment with SSRI antidepressants. It is also uncertain whether psychopharmacology has a role in preventing suicidal behaviour in people with personality disorders. Despite the limitations of the evidence we contend that suicide risk should be an important factor in deciding when and what to prescribe.