The suicide attempts were assessed in 32 schizophrenic patients on whom the dexamethasone suppression test (DST) was done twice in the course of illness: in the years 1985–91 and 1996–97. In the 1985–91 period, both baseline and post-dexamethasone cortisol levels were significantly higher in the patients with previous suicide attempts and baseline cortisol was higher in the patients who were to make a future attempt. In 1996–97, DST non-suppression was shown in more than half of the patients with a history of suicide attempt and in none of those without such history: all cortisol levels were significantly higher in the patients with a history of suicide attempt. Although the mean intensity of depression was higher in the patients with a history of suicide attempt, no association between the intensity of depression and present or previous DST non-suppression status was found. It is suggested that the hyperactivity of the hypothalamic-pituitary-adrenal axis may constitute an element of diathesis for suicidal behavior in schizophrenic patients.