608 patients admitted to a general Intensive Care Unit (ICU) over a 30 month period were analyzed according to the Apache II Severity of Disease Classification System on day one of admission. Hospital outcome details were available on 583 patients in the series. The mean Apache II scores for survivors (396) and non-survivors (187) were 13 (SD 7) and 24 (SD 9), and their Risk of Death were 16 (SD 16) and 47 (SD 27) respectively (p less than 0.001 for both). The majority of deaths (75%: 141/187) in our series came from those with chronic ill health (55%: 103/187), of whom 37% (38/103) were in endstage disease, and those with "old" trauma (18%: 34/187) often with incipient sepsis transferred from other hospitals after a mean delay of 9 days. Our higher than predicted mortality (mortality ratio 1.2) in comparison with centres in the United States of America (US) may be partly explained by the high proportion of our population from these unfavourable groups, by our use of the best Glasgow Coma Scale in the first 24 h following admission, and the major differences between our patient population and that of the US upon which the Apache II was based. The presence of these large unfavourable groups indicates a change in our admission policy is warranted.