A Classification of suicidal behaviour was derived by cluster analysis from descriptive data on parasuicide patients. The grouping was meaningful in terms of clinical interpretation and had both therapeutic and prognostic implications. The sample was broken down into three groups, identified as repeated, serious and non-serious attempts. The repeated attempters had the worst prognosis at 1 -year follow-up. When the sample was classified into five groups according to seriousness of the attempts, the repeater and non-serious groups were retained, while the serious attempts were split into three subtypes, which differed on nosological characteristics, treatment disposal and outcome. An excessively high successful suicide rate was found in a small group of elderly attempters.