Background: UGI bleeding is one of the most common encountered emergencies in day to day practice. Criteria for early endoscopy had been published for years but it may not be proper for all hospitals in Thailand.Objective: To evaluate usefulness and cost effectiveness of early endoscopy in diagnosis and treatment in the patient groups.Methods: A prospective study was performed to find the result of early endoscopy in patients who admitted with UGI bleeding during the year 2006-2007. 1,341 patients (791 men, 550 women) with UGI bleeding underwent urgent endoscopy. We  classified patients into 3 groups : group I : patients who had endoscopy after 24 hrs , group II : patients who had endoscopy between 12-24 hrs and group III : patients who had endoscopy within 6-12 hrs. The datas including endoscopic findings, therapeutic methods and outcomes were collected and compared among the three groups.Results: Majority of patient was over 50 yrs. Most of bleeding sites were bleeding peptic ulcers and bleeding esophageal ulcers. Stigmata of active and recurrent bleeding especially large varices were found more in group II and III patients. Five patients with variceal bleeding died from sepsis and hepatic failure.Conclusion: Within 24 hrs endoscopy is the proper time after resuscitation. The finding showed the evidence of active and stigmata of recurrent bleeding, Available interventional equipments should completely prepared before endoscope in these patients’ group. Outcome of within 24 hrs endoscopy were slightly higher in hospital cost, but not in length of hospital staying. Patients with low-risk lesions found on endoscopy (group I) can be discharged earlier or treated safely as an outpatient and less expensively compared with hospitalized patients.