A retrospective audit of 200 transfusion episodes involving the use of platelets or fresh frozen plasma (FFP) was performed in five hospitals in London. It examined the currently used practices of transfusion and assessed the appropriateness of blood component treatment. It was necessary to search for an excess of case notes to provide a sufficient number of patients for review. In 61.5% of cases the reason for using the components was not stated. Inadequate documentation of the use of blood components occurred in 66% of cases. An accepted clinical indication for the use of components was evident in only 36% of the total; inappropriate use of FFP was particularly apparent. It is concluded that many aspects of transfusion practice need to be improved.