In this article a study is reported of 12 suicides committed by psychiatric in-patients during their treatment in the therapeutic communities Rijnland (for adults) and Amstelland (for adolescente) in the years 1972-1974, made by a group of collaborators of these therapeutic communities. Amstelland and Rijnland form the Division for Residential Psychotherapy of the Provinciaal Ziekenhuis at Santpoort. After a review of the relevant literature, short case- histories of the suicidants are given. The circumstances under which they committed suicide and the reactions of patients and staff are discussed and commented on. In the last paragraph the main conclusions of the study are summoned. The first conclusion is that the main aim of psychiatric treatment is not the absolute prevention of suicide. The treatment of a suicidal patient aims at establishing sufficient responsability for one's own life. To achieve this, risks must be taken. As in surgery, one has in psychiatry to calculate the risks involved in treating a specific suicidal patient. These risks are located in the patient, in the the way he or she is treated and in the environment in which the treatment takes place. Selection of suitable patients, adequate and conscientious treatment and a good control of the environment are necessary. Recommandations relevant to these points are made. Separately the scenario is reported that is used at Amstelland for the handling of suicidal crises and of suicide.