The worldwide scarcity of intensive care therapy leads to the rationing of this expensive resource. This prospective study investigates the rationing of intensive therapy at the University Hospital of the West Indies (UHWI) by recording triage decisions for intensive care unit (ICU) admission and the impact of these decisions on patient outcome. Between June 2001 and May 2002, all patients triaged for admission to a multidisciplinary ICU were studied. For each patient, data were collected including APACHE II score, ICU resource availability and patient survival. There were 356 eligible requests, and 285 (80%) were admitted to the ICU, with 73 (26%) of these admitted patients receiving intensive care outside of the ICU due to space limitations. The APACHE II score was the strongest predictor of ICU admission, with admission more likely as the score decreased (odds ratio = 0.94, 95% confidence interval 0.91, 0.98, p = 0.001). Of 311 requests considered suitable for admission, 26 (8%) were refused admission due to resource limitations. Mortality among these eligible refusals was 81%, compared to 34% among admitted patients (p < 0.001). Although triage decisions are based predominantly on a patient’s disease severity, the demand for ICU space exceeds supply, and patient care is negatively impacted by this imbalance.