Objectives: To determine whether the introduction of the Medical Emergency Team (MET) system designed to provide immediate help for seriously ill patients: (i) changed the pattern of ICU patient transfers from the wards; and (ii) improved hospital survival rates. Methods: Prospective information on MET calls and unanticipated ICU transfers was collected for 3 years in a suburban metropolitan hospital. Results: A 3-year review of MET showed the number of MET calls doubled in the second and third year and the team was activated for more than just the most extremely ill patients. Whilst the frequency of calls for cardiopulmonary arrest remained constant (n=16), increased use of the MET resulted in the proportion of calls for cardiopulmonary arrest dropping from 30% in year 1 to 13% in year 3. A slight decrease in the percentage of in-hospital deaths (0.74% in year 1 to 0.65% in year 3) was also demonstrated. The incidence of cardiopulmonary arrest per hospital admission also decreased slightly (0.08-0.07%). Although the overall number of ICU transfers remained constant, more seriously ill patients were transferred to ICU via the MET system. This was accompanied by a significant fall in unanticipated ICU transfers. Whilst the reduction in hospital deaths was encouraging, this study could not demonstrate whether the slight improvement in hospital survival rate over the 3 years was due to the MET system. Conclusion: More information is needed to demonstrate that the MET system improves patient survival. The study also highlights the importance of taking proactive measures, which should include providing in-service education on the benefits of early identification and treatment of patients who are at risk of acute deterioration, raising awareness and changing attitudes in hospitals when introducing system such as the MET. �� 2001 Elsevier Science Ireland Ltd.