One hundred and fifty four consecutive adult patients having cardiac surgery for a variety of cardiac lesions were evaluated prospectively for postoperative jaundice, those with a raised preoperative serum bilirubin concentration (greater than 34 ,mol/I or 2 mg/100 ml) being excluded. The incidence of early postoperative jaundice, as defined by a serum bilirubin concentration of 50 ,umoUl (3.0 mg/100 ml) or greater, was 23*4%. The jaundice was mild (bilirubin concentration 51-100 ,umoll (3-.06.0 mg/100 ml)) in 26 patients (16.9%) and moderate to severe (greater than 100 ,umol/I (6.0 mg/100 ml)) in 10 patients (6-5%). Important contributing factors were the preoperative severity of right heart failure (raised right atrial 'pressure at heart catheterisation) and hypotension or hypoxaemia and the amount of blood transfused during or shortly after surgery. Age, sex, underlying cardiac lesion, whether halothane was used, operative procedure, duration of cardiopulmonary bypass, and presence or absence of hepatitis B surface antigen were not predictive of postoperative jaundice.It has long been recognised that transient jaundice could appear after a surgical procedure' and that hepatic damage is particularly liable to follow cardiopulmonary bypass.23 In one retrospective study early jaundice was seen in 13% of 232 patients undergoing open heart operations.4 In a similar study 8.6% of 736 patients undergoing open heart surgery developed postoperative jaundice.5 There have, however, been only a few prospective inquiries into the incidence and causes of postoperative jaundice. The prospective study of Evans et a16 revealed a much higher incidence (21%) of postoperative jaundice in patients having major noncardiac operations. The true incidence of early jaundice after open heart surgery is therefore still unclear and awaits further study.Furthermore, all studies on jaundice after open heart surgery were reported more than 10 years ago, when the medical care of patients undergoing open heart surgery was not as good as today, and when the hepatitis B surface antigen (HBsAg) was not recognised.7 HBsAg carriers are now known to harbour various liver lesions,8 which might contribute to the development of postoperative jaundice.9 It seemed therefore pertinent to investigate this prob-