Background: Major depressive disorder is the one of most important in mood disorder.It is second burden of disease in worldwide behind cardidovascular disease in 2020 and 90% of completed suicide patients are diagnosed some psychiatric co-morbidity especially major depressive disorder.Obiective: This project studied about suicide behaviours of Major Depressive disorder patient.Methods: It was retrospective descriptive study for three years in 2006-2008 at suansaranrom psychiatric Hospital, southern Thailand.235 subjects were patient that was diagnosed by psychiatrist were major depressive disorder.The investigator collected data within inclusion criterian by himself.Study instruments were included general patient data, medical investigation data and diagnostic data.Analysis by frequency distribution and percentage.Results: Most subjects were female(69.8%) age 36-45(36.1%) lived in suratthani province(44.3%) that race(99.6%) buddhism(96.4%) marriage(72.3%)Primary school (53.2%)agriculturist(14.1%) duration before treatment is 1-3 months(48.1%) personality problems (36.6%) medical comorbidity(25.1%) psychiatrict comorbidity(36.6%) genetic history(13.2%) substance use(20.4%) investigation(11.1%).Mostly was diagnsed by clinical experience more criterian (DSM) diagnosis.133 depressed subjects had suicidal idea and/or plan and/or attempt (56.6%).The most suicidal method was ingestion such as drugs or chemicals (43%) followed by hanging (37%) and cut or stab (14%).Conclusion: Mostly depressed patients were diagnsed by clinical experience.Suicide idea, plan or attempt was common symptom of major depressive disorder at suansaranrom psychiatric Hospital, southern Thailand and mostly suicidal attempt method was ingestion.