This prospective, cohort study assessed the independent predictors of in-hospital mortality in patients with acute upper gastrointestinal haemorrhage admitted to the medical intensive care unit (MICU) at the University Clinical Centre Maribor, Slovenia. Using univariate, multivariate and logistic regression methods the predictors of mortality in 54 upper gastrointestinal haemorrhage patients (47 men, mean ± SD age 61.6 ± 14.2 years) were investigated. The mean ± SD duration of treatment in the MICU was 2.8 ± 2.9 days and the mortality rate was 31.5%. Significant differences between nonsurvivors and survivors were observed in haemorrhagic shock, heart failure, infection, diastolic blood pressure at admission, haemoglobin and red blood cell count at admission, and lowest haemoglobin and red blood cell count during treatment. Heart failure (odds ratio 59.13) was the most significant independent predictor of in-hospital mortality. Haemorrhagic shock and the lowest red blood cell count during treatment were also important independent predictive factors of in-hospital mortality.