We conducted a postal survey of all National Health Service centres where cardiac surgery is performed. We requested information about the priming solutions and additives used in the cardiopulmonary bypass circuit, and specifically asked whether changes were made in priming solutions for diabetic patients. Hartmann's solution was used by 63% of respondents, either alone or mixed with colloid. Heparin was added to the prime by 89% of respondents. Only two centres and one anaesthetist at a third centre altered the prime for diabetic patients.