Background: Depression is the most common psychiatric disorder in people with suicidal behavior. The knowledge of its risk factors should help to design preventive strategies. Aim: To describe suicidal behavior and risk factors for attempted suicide in people with major depressive disorders (MDD). Material and Methods: A 12-month follow-up study was conducted in 112 outpatients at three psychiatric care centers of Chile, with baseline and quarterly assessments. Demographic, psychosocial and clinical factors as potential risk factors of suicide attempts, were assessed. A clinical interview with DSM-IV diagnostic criteria checklist, Hamilton Depression Scale and the List of Threatening Experiences and Multidimensional Scale of Perceived Social Support were applied. Results: Sixty seven percent of participants had suicidal ideation and 43.8% had attempted suicide. Suicide risk was significantly higher in participants with a single major depressive episode (odds ratio (OR)= 3.98; 95% confidence intervals (CI)= 1,29-12,32 p= 0.02) and those with previous suicide attempts (OR= 13.15; 95% CI= 3,87-44.7 p < 0.01)). Young age, not having a partner, being unemployed, having a severe major depressive episode, having psychotic symptoms, having a personality disorder and being devoid of medical illness increased the risk of suicide attempts, but they did not reach statistical significance. Conclusions: Significant risk factors should be specially considered when designing suicide preventive strategies in patients with MDD.Background: Depression is the most common psychiatric disorder in people with suicidal behavior. The knowledge of its risk factors should help to design preventive strategies. Aim: To describe suicidal behavior and risk factors for attempted suicide in people with major depressive disorders (MDD). Material and Methods: A 12-month follow-up study was conducted in 112 outpatients at three psychiatric care centers of Chile, with baseline and quarterly assessments. Demographic, psychosocial and clinical factors as potential risk factors of suicide attempts, were assessed. A clinical interview with DSM-IV diagnostic criteria checklist, Hamilton Depression Scale and the List of Threatening Experiences and Multidimensional Scale of Perceived Social Support were applied. Results: Sixty seven percent of participants had suicidal ideation and 43.8% had attempted suicide. Suicide risk was significantly higher in participants with a single major depressive episode (odds ratio (OR)= 3.98; 95% confidence intervals (CI)= 1,29-12,32 p= 0.02) and those with previous suicide attempts (OR= 13.15; 95% CI= 3,87-44.7 p < 0.01)). Young age, not having a partner, being unemployed, having a severe major depressive episode, having psychotic symptoms, having a personality disorder and being devoid of medical illness increased the risk of suicide attempts, but they did not reach statistical significance. Conclusions: Significant risk factors should be specially considered when designing suicide preventive strategies in patients with MDD.