Reported first case of suicide with radioactive substance in Bulgaria. Male, aged 30, defectoscopist, with cyclothymic structure of character and psychotraumatic family environment made a second and successful attempt at suicide, this time by means of outer irradiation with cesium-137 with an activity of 5.3 curie in the course of two hours--irradiated his heart region and the first three fingers of his right hand. A grave picture of acute, local irradiation injury lasting four months with lethal outcome. The authors treat the psychological motives in the behaviour of these suicides and the reasons which determine the small number of suicide carried out with radioactive substance.