The aim of this study was to define the status of preoperative zinc levels in patients with heart disease presenting for cardiac surgery and to identify any predictors for and any clinical consequences of low zinc levels.Adult patients presenting for elective surgery, either coronary artery bypass graft surgery and/or valve replacement, provided a fasting blood sample on the day of admission for surgery. Plasma and erythrocyte zinc levels were analysed and the levels correlated with the patient's characteristics and clinical outcomes.Of 56 patients 53% (n=30) had abnormally low plasma zinc levels (<12μmol/L) and 5.5% (n=3) had abnormally low erythrocyte zinc levels (<160μmol/L), indicative of deficiency. There were significant associations between lower plasma zinc levels and the presence of hypertension (p=0.02), hypercholesteraemia (p=0.02) and higher body mass index (BMI) (p=0.034) but no effect on major postoperative clinical outcomes.This small study shows that zinc deficiency is common in cardiac surgery patients, especially in the presence of hypertension, hypercholesterolaemia or obesity. The effects of zinc deficiency in cardiac surgery need to be further investigated.