Objective: To assess one year mortality of the patients (pts) treated for acute illness by a Mobile Intensive Care Unit (MICU) * .Methods: Data collected from all pts treated for non-traumatic acute illness by the MICU in 1994 were investigated and mortality was recorded one year after the initial contact.Results: 2.791 different pts were served by the MICU in 1994. 396 pts were not treated but pronounced dead at the site. 91 pts were treated and survived the actual incident but could not be included in the study due to lack of registration or foreign status. The status of the remaining 2.304 treated pts in relation to initial organ failure are shown below:Within the heart group 28% of the pts with ischaemic heart disease (445 pts) and 35% of 142 pts with heart failure, died. COPD (321 pts) with a mortality of 31% dominated the respiratory disease group. Vascular disease (192 pts) with a mortality of 44% was the major reason of death within the CNS group. This group includes 112 children with febrile convulsions.Conclusions: Prehospital treatment of acute illness is dominated by relatively few diagnoses, mostly in elderly people (mean age 70 years), presenting high mortality.