We retrospectively studied the relationship between organ system failure, sepsis, sex, age, length of stay, initial diagnosis at admission, number of organ system failures, pre-existing chronic disease, and mortality in 499 admissions to a medical intensive care unit (ICU) in order to assess their validity to predict the outcome of ICU stay. Mortality referred to death in the ICU only: 160 (32 %) of the 499 patients died in the ICU and 339 (68%) were transferred onto the general medical wards. Sepsis was found to be a good predictor of mortality (p < 0.01) as were the other predictors of death, that i.e. is, neurological, cardiovascular and pulmonary failures (p<0.05, p<0.10, p<0.10, respectively).