The diagnoses of 8895 patients who were admitted for intentional self-poisoning with psycho-active drugs were studied in order to find predictors for subsequent completed suicide and repeated self-poisoning. Automated record linkage by means of the Swedish personal identification numbers was performed between the Stockholm County inpatient registry and the cause-of-death registry. With Cox regression models, several diagnostic predictors were identified although they were generally unspecific and insensitive. This may be due both to the low base rate of suicides, and to the omission of other more powerful non-clinical predictors, such as personality traits, hopelessness and social disruption. It is concluded that secondary psychiatric prevention may still be justified, although it will be applied to large numbers of patients who will not eventually commit suicide or repeat self-poisoning.