The prediction of suicide remains a major challenge for health professionals. Sociodemographic predictors of the risk of suicide lack specificity: factors such as living alone, being unemployed, or having a physical or mental illness are common, separately or in combination, but suicide is rare. Psychiatric conditions, such as depression, alcohol dependence, schizophrenia and personality disorders, are strongly associated with suicide, but most psychiatrically ill patients do not suicide. Most suicidal patients consult a helping agency within a month of their act and, in practice, successful assessment of the risk of suicide and intervention to prevent it depend on gaining an understanding of the individual patient and developing a therapeutic relationship. More research into the biological, psychological and social factors that distinguish suicidal from non-suicidal individuals is needed. We review key studies that have addressed the issue of suicide prediction, outline the clinician's role in evaluating the risk of suicide in the individual, and suggest directions for future research.