Background Some depressed people die by suicide although they are in treatment. The aims of this study were to examine the prevalence of suicidality and to identify the associated social, demographic and clinical factors in Thai patients with acutely treated depressive disorders.Patients and methods A sample of 178 in- and outpatients with depressive disorders who were treated within the six-month period of being diagnosed or of a recurrent episode were recruited from a tertiary hospital during November 2017 to April 2018. The associations between suicide risks assessed using the suicidality module of the Mini-International Neuropsychiatric Interview (MINI) and various factors including demographic data, depressive severity, interpersonal problems, social support, family relationships, and life stress events were analyzed by chi-square test. Logistic regression was used for identification of the potential predictors of moderate-to-high suicide risk.Results Most of the subjects were single (80.9%), female (68%), and in early adulthood (mean age 28.9, SD 11.2). The prevalence of suicidal ideation, suicide attempt within one month, and previous history of suicide attempt during lifetime were 62.4%, 35.4% and 41%, respectively. The prevalence of suicidality (76.4%) and moderate-to-high suicide risk (48.4%) were high. The factors associated with moderate-to-high suicide risk were lower age, no religion, unemployment, history of substance use within one year, moderate-to-severe level of depression, being an in-patient, short duration of treatment, receiving benzodiazepines, having interpersonal role disputes, having interpersonal deficits, low social support, poor family relationships and functioning, and high severity level of health stress events. Potential predictors of moderate-to-high suicide risk were moderate-to-severe levels of depression, poor family relationships and functioning, age of 20 or lower, being an in-patient, and receiving benzodiazepines.Conclusion The prevalence of suicidality in patients with acutely treated depressive disorder was found to be high. Depressive severity and social factors such as poor family relationships were highly associated with suicide risk. Knowledge of these factors may raise awareness of suicide prevention during the course of treatment of depression.