The ability of the Acute Physiology And Chronic Health Evaluation (APACHE) II scoring system to predict outcome in 199 critically ill patients with trauma but without head injury was assessed prospectively over an 8-month period. Some 178 patients (89.4 per cent) underwent operation and 50 (25.1 per cent) died, 44 after operation and six without undergoing surgery. The mean(s.d.) APACHE II score was 8.0(5.2) for survivors and 14.5(5.5) for non-survivors (P < 0.001). In patients who underwent surgery the mean(s.d.) scores were 7.7(4.6) and 13.4(5.5) (P < 0.001) and for those managed without operation 11.1(7.2) and 14.7(6.3) (P = 0.31) in survivors and non-survivors respectively. The predicted risk of death and observed mortality rate were 5.1 and 25.1 per cent respectively for the entire group, 5 and 25 per cent for patients undergoing surgery, and 7 and 29 per cent for those not operated on. Although the APACHE II system correctly identified all survivors (specificity 100 per cent), it failed to predict death in any patient (sensitivity 0 per cent). The results suggest that this objective prognostic scoring system is not applicable to the patient with trauma who does not have concurrent head injury.