During a dengue outbreak in 2005 in the East-coast region of Peninsular Malaysia, one of the worst hit areas in the country at that time, we undertook a prospective study. We aimed to describe the bleeding outcome and changes in the liver and hematologic profiles that were associated with major bleeding outcome during the outbreak. All suspected cases of dengue admitted into the only referral hospital in the region during the outbreak were screened for WHO 2002 criteria and serology. Liver function, hematologic profile and severity of bleeding outcome were carefully documented. The association between symptoms, liver and hematologic impairments with the type of dengue infection (classical vs. hemorrhagic) and bleeding outcome (major vs. non-major) was tested. Dengue fever was confirmed in 183 cases (12.5/100,000 population) and 144 cases were analysed. 59.7% were dengue hemorrhagic fever, 3.5% were dengue shock syndrome and there were 3 in-hospital deaths. Major bleeding outcome (gastrointestinal bleeding, intracranial bleeding or haemoptysis) was present in 14.6%. Elevated AST, ALT and bilirubin were associated with increasing severity of bleeding outcome (all P < 0.05). Platelet count and albumin level were inversely associated with increasing severity of bleeding outcome (both P < 0.001). With multivariable analysis, dengue hemorrhagic fever was more likely in the presence of abdominal pain (OR 1.1, 95% CI 0.02-1.6) and elevated AST (OR 1.0, 95% CI 1.0-1.1) but the presence of pleural effusion (OR 5.8, 95% CI: 1.1-29.9) and elevated AST (OR 1.008, 95% CI: 1.005-1.01) predicted a severe bleeding outcome. As a conclusion, the common presence of a severe hemorrhagic form of dengue fever may explain the rising death toll in recent outbreaks and the worst impairment in liver and hematologic profiles was seen in major bleeding outcome.