Readmission is a frequent problem following cardiac surgery, ranging between 7 and 20%. A retrospective analysis of patients who underwent cardiac surgery at Monash Health between 2008 and 2023 was performed. 799 (11.3%) patients who were discharged were readmitted to hospital within 30 days of discharge. Patient who were readmitted were more likely to have diabetes (40.6% vs 31.3%, p<0.01), worse preoperative renal function (Creatinine 119.4+/-129.9ug vs 97.2+/-73.5ug, p<0.01), longer bypass times (118.3+/-52.5 vs 111.1+/-51.5 minutes, p<0.01) and higher rates of post-operative Atrial Fibrillation (34.2% vs 22.2%, p<0.01). Reason for readmission included arrhythmias 64 (8.0%), heart failure 29 (3.6%), incisional complications 169 (21.2%), and respiratory complications including pneumonia 104 (13.0%). More than 10% of patients who undergo cardiac surgery require hospital readmission within a month of procedure. This adds significantly to the resource utilisation of cardiac surgery. Prevention of post-operative and post-discharge arrhythmia, health care associated infections including incisional and respiratory complications, and targeted management of patients with poorly controlled diabetes and impaired renal function present important targets for future quality improvement.