The role of preoperative haemoglobin as a predictor of short-term and long-term outcomes after cardiac surgery has been well established. Anaemia can impede a patient's ability to recover fully and participate in postoperative rehabilitation. It has been found that patients with a normal haemoglobin level may become anaemic during surgery. An evaluation of patients undergoing cardiac surgery, i.e. CABG, valve or combined CABG-valve procedures showed that there was a decrease in mean haemoglobin level pre-surgery two and four days after surgery. To date, no prospective randomised clinical study in cardiac surgery assessing the effect of intravenous iron supplementation in patients undergoing cardiac surgery has been reported. This prospective, randomized, placebo controlled, double blind study is planned to evaluate the effect of intravenous iron isomaltoside 1000 (Monofer®) in comparison with placebo in non-anaemic patients undergoing cardiac surgery.