['When patients return to the emergency department (ED) shortly after being seen, it is generally assumed that their initial evaluation or treatment was inadequate.', 'The purpose of this study was to determine the rates and causes of revisits to the ED of a 710-bed secondary teaching referral hospital (Kuang Tien General Hospital), to identify areas for improvement, and to define the initial ED presentations that are associated with such revisits.', 'The study period was from January 1, 2006 to December 31, 2006. There were 34,714 patients seen and discharged in the ED; 1899 patients returned within 72 h. Monthly revisit rates were calculated. The patients who revisited the ED within 72 h were retrospectively identified by the authors, and their charts were examined to determine the causes of the revisits.', 'There were 1899 patients (5.47% of total) found to have revisited the ED within 72 h after their initial visit. The monthly revisit rates ranged from 2.85% to 6.25% (average, 5.47%). The rates of revisits that were related to factors of illness, patients, and doctors were 80.9%, 10.9%, and 8.2%, respectively. Among the factors related to doctors, 3.7% (70 cases) were misdiagnosis, and abdominal pain was the most common presentation (55.7%, 39/70). The most common initial ED presentations were for abdominal pain (12.9%), fever (12.6%), vertigo (4.5%), headache (2.1), and upper respiratory infection (2.1%).'] Does unplanned emergency department revisit within 72 hours to a secondary teaching referral hospital in Taiwan?