Objectives: The effect of preoperative smoking status on the outcome of cardiac surgery remains unclear. Preoperative cessation may be associated with reduced postoperative pulmonary complications and in older patients preoperative smoking status appears to have a greater impact on outcome. This study was designed to assess the relationship between age, preoperative smoking status and outcomes from cardiac surgery. Methods: We performed a single-centre, retrospective cohort study to compare in-patient cardiac surgical mortality and morbidity in current smokers and never-smokers. We analysed the cardiac surgical population in its entirety and in age-stratified subsets using univariate and logistic regression analyses. Results: During a five-year period ending March 2007, 10.8% of all patients (n=554) undergoing cardiac surgery were current smokers. Five hundred and fifty-four never-smokers undergoing cardiac surgery during the same period were identified. Overall, the smokers had a tendency towards higher in-patient mortality (4.3 vs. 2.3%, P=0.067) and increased rates of morbidity. Amongst over 70-year-olds, the current smokers had significantly higher rates of pulmonary complications (24.7 vs. 8.2%, P<0.0002), new renal replacement therapy (17.3 vs. 3.1%, P<0.0001) and infections (44.4 vs. 23.8%, P<0.0007). They had longer intensive care stay (6.2 vs. 2.8 days, P=0.002) with more intensive care unit readmissions (19.8 vs. 5.2%, P<0.0002) and significantly increased in-patient mortality (14.8 vs. 2.1%, P<0.0001). In the elderly smokers, mortality was significantly associated with the rate of pulmonary complications (P=0.03). Preoperative smoking status remained a predictor of pulmonary complications after logistic regression. Conclusions: The current data strengthen the observation that preoperative smoking status is predictive of adverse outcomes of cardiac surgery in the elderly. Further study into the effect of preoperative smoking cessation in the elderly may inform cessation counselling and the timing of surgery.