BackgroundThe lifetime risks of suicide are generally quoted as 15% for affective disorder and alcoholism and 10% for schizophrenia, based on data from 1921–1975 and on calculations performed before computerised modelling techniques became available. This study recalculates the risk using contemporary data and modern techniques.MethodTwenty-seven mortality studies provided data for affective disorder, 27 for alcohol dependence and 29 for schizophrenia. The proportion of the cohort who had died was plotted against the proportion of deaths from suicide. Modelling techniques fitted curves through the data points extrapolating them to cohort extinction, thus estimating the lifetime risk of suicide for each disorder.ResultsThe lifetime risk was estimated at 6% for affective disorder, 7% for alcohol dependence and 4% for schizophrenia.ConclusionsThe lifetime suicide risk figures often quoted in the literature appear to be too high.