Acute upper gastrointestinal bleeding (UGIB) is a major gastroenterological problem in Thailand. Peptic ulcer has remained the leading cause of UGIB, followed by acute mucosal erosions, and variceal bleeding. In the present study, covering the period between 1980 and 1984, early endoscopic diagnosis was obtained in 82% of cases, while conservative treatment was effective in 83.6%. Factors associated with increased mortality were advanced age, shock, sepsis nonsteroidal anti-inflammatory drug (NSAID) ingestion, severe blood loss, associated diseases and surgical treatment. The overall mortality was 6.7 percent.