Journal of the Medical Association of Thailand Vol 94, No 12:DECEMBER 2011 (SUPPL. 7) 0125-2208 94 12 2011 Dec Characteristics of Unscheduled Emergency Department Return Visit Patients within 48 Hours in Thammasat University Hospital 73 EN Intanon Imsuwan Original Article To determine rate, common initial presentation and cause of unscheduled emergency department return visits within 48 hours at Thammasat University Hospital. The present study design involves retrospective observational study of patients who returned to the Emergency department (ED) within 48 hours after being discharged from the ED. Data was collected from August 1, 2009 to July 31, 2010. Patient age, gender, triage level, patient-in time, patient-out time, length of stay, chief complaint, first and second visit diagnoses and disposition after second visit were recorded by chart review. The factors and causes of revisits were classified by the author as illness-related, patient-related, doctor-related and/or healthcare system-related. A total of 307(0.92%) patients returned visit to the ED within 48 hours during August 1, 2009 to July 31, 2010. The most common chief complaint were dyspnea (75 cases or 24.4%), abdominal pain (53 cases or 17.3%), bleeding per vagina (28 cases or 9.1%). The rates of revisit that were related to factors of illness, patients, doctors and healthcare system were 60.6, 8.5, 28.3 and 2.6, respectively. Chi-squared was used for categorical data. Unscheduled ED return visit patients represent high risk patients. Patients in this group are associated with various factors. The present study indicates that the most common factor behind return visits were illness-related. Illnessrelated and patient-related factors were significantly associated with discharged patient. Observational units could reduce unnecessary return visit in this group. Doctor-related and healthcare-related factors were significantly associated with admitted return visit patients. Emergency physician training system and guideline implementation for doctors could reduce unexpected early discharge in this group. Return visits Emergency Department