INTRODUCTION: Electronic cigarettes (e-cigarettes) may reduce tobacco use and achieve tobacco abstinence in the perioperative period of cardiothoracic surgery for patients who smoke. However, research on patients' views on the role of e-cigarettes as a smoking cessation tool is lacking. This mixed-methods study explored perceptions on the use of e-cigarettes among current smokers and ex-smokers awaiting cardiothoracic surgery in Australia. METHODS: A cross-sectional study and semi-structured interviews were conducted with 62 patients who were diagnosed with coronary artery disease or lung cancer and were scheduled for elective cardiothoracic surgery at six metropolitan hospitals in Sydney. Data were collected on demographic characteristics, smoking history, surgical risk index, self-efficacy, interest in, perceived benefits of, and barriers to using e-cigarettes in the perioperative period. RESULTS: Current smokers reported significantly higher interest in the use of e-cigarettes (p=0.008), and perceived fewer barriers (p=0.048) and more health benefits (p=0.079), compared to ex-smokers. Current smokers considered e-cigarettes to be either a safer alternative to tobacco or a novel method for quitting. Recent ex-smokers, defined as those who quit 2-8 weeks, were a distinct group with high nicotine dependency, a long history of smoking, and multiple failed quit attempts. Compared to longer-term ex-smokers (8-52 weeks quit), recent ex-smokers were more interested in e-cigarettes (p=0.029) and considered e-cigarettes a useful aid to prevent relapse in the lead up to surgery and to manage their nicotine cravings. CONCLUSIONS: E-cigarettes may be considered a short-term novel aid and a bridge to evidence-based methods to reduce harm from continued tobacco use for some patients awaiting cardiothoracic surgery for coronary artery disease or lung cancer. This study presents reasons why patients awaiting cardiothoracic surgery may enquire about or use e-cigarettes, which will help clinicians identify those who need more consistent, sustained cessation support.