Transfusion medicine is an art as well as a science. Standards, guidelines and general principles are essential, but individual circumstances and individual problems continue to fall outside these general rubrics. Through the "Questions and Answers" service, the US Scientific Section Co-ordinating Committee provides Association members and non-members with expert opinions about specific issues and concerns. The questions and answers in this publication cover a wide range of topics, reflecting more than a year of correspondence and the responses of experts in many fields. On numbers alone, topics that provide the most uncertainty or concern seem to be: administration of blood and components, pretransfusion testing and principles of transfusion practice. Far more questions this year than in previous years involve autologous transfusion and quality assurance of transfusion practice, but queries about prenatal and perinatal testing have declined.