Summary This prospective observational study was conducted to assess the current transfusion practice in critically ill patients. One thousand two hundred and fortyβseven consecutive critically ill patients admitted between February 1999 and October 1999 were included in the study. Overall 666 (53%) patients were administered red cells. Transfused patients had significantly higher intensive care unitβ£mortality but also had higher Acute Physiology and Chronic Health Evaluation II scores and longer durations of stay. The average pretransfusion haemoglobin concentration wasβ<β9βg.dl^β1^ in 75% of transfusion episodes. The common indications for transfusion were low haemoglobin (72%) and haemorrhage (25%). Overall, 202 (16%) and 281 (22%) of the patients were transfused platelets and fresh frozen plasma, respectively. The indications for transfusion were haemorrhage, low platelet counts, prolonged prothrombin time or to provide cover for invasive interventions. Most platelet transfusions were given at values in the order of 50β100βΓβ10^9^.l^β1^. The pretransfusion platelet count varied according to the indications for transfusion. This study showed that transfusion practice is consistent and that in general there does not seem to be an excessive use of blood components in critically ill patients.