OBJECTIVE : Patients attempted suicide by psychotropic drug overdose and require medical care have increased, becoming a serious problem in Japan. This study investigated the characteristics of patients who attempted suicide by overdose and required emergency care, with a focus on quantity of drugs taken. METHODS : We conducted a clinical survey of 98 patients examined at the emergency centre of the psychiatric department of Jichi Medical University Hospital and hospitalized for attempted suicide by drug overdose from January 1, 2012 to December 31, 2014. Data were collected by chart review and subjected to statistical analysis. RESULTS : Diagnoses were mainly mood disorder and neurosis in both genders. Also, 23.5% of the cases had multiple hospitalizations at the centre, and past overdose was significantly higher in these patients. The average total number of pills/sachets ingested was 84.4 ± 95.5, but no significant difference was noted in dosage according to psychiatric clinic visit history (P = 0.63). Of these patients, 45.1% returned to their previous hospital, and 12.2% were hospitalized in the psychiatric ward. CONCLUSIONS : These results are consistent with reports in the literature. Psychiatric outpatient history does not seem to be a risk factor for attempted suicide by ingesting higher drug doses.