This retrospective study aimed to determine the prevalence of preoperative anaemia, hypochromia and microcytosis in cardiac surgery patients. Data was analysed for 943 patients (over a two-year period) undergoing coronary artery bypass graft, valve or combined coronary artery bypass graft and valve surgery at a tertiary hospital in South Australia. Overall prevalence of preoperative anaemia was 25.2%, greater in males than females (27.6 vs 19.9%, P <0.01). Of patients with preoperative anaemia, 19.3% had reduced red cell indices (mean corpuscular haemoglobin and/or mean corpuscular volume) compared to 4% of patients without anaemia. The proportion of anaemic patients with low red cell indices was significantly higher in women <50 years and 50-65 years, compared to those >65 years of age (P=0.003). Anaemic patients with low red cell indices had lower preoperative haemoglobin than anaemic patients without low red cell indices (median haemoglobin 112 vs 120 g/l, P=0.008). Compared to non-anaemic patients, anaemic patients had higher transfusion rates (79.8 vs 46.4%, P <0.0001), which were greater in those with reduced red cell indices compared to those with normal red cell indices (93.5 vs 76.6%, P=0.01). This study demonstrated a high prevalence of preoperative anaemia, microcytosis and hypochromia in cardiac surgical patients.