Background Same-day cancellation of cardiac surgeries is a disheartening experience for patients. The primary aims of this study were to determine the frequency and reasons for same-day cancellations, and associated patients’ outcomes. The secondary aims were to evaluate patients’ reactions to cancellations and to propose measures to reduce cancellations. Methods We prospectively reviewed all elective and urgent in-patient adult cardiac surgeries performed from August 2017 to March 2018. Procedures were divided into cancelled (C) and not cancelled (NC) groups. A qualitative patient satisfaction survey was undertaken. Results Overall, 1388 patients were scheduled for cardiac surgery during this period. Elective surgeries constituted 70.7% (981/1388) and urgent 29.3% (407/1388). 231/1388 (16.7%) procedures were cancelled for the following reasons: 30.5% lack of ITU beds, 20.1% patient medically unfit, 8.2% ITU staff shortage, 6.9% emergency case intervention and 34.2% other. There was no significant difference in mortality between groups (2.6% in C vs 1.6% in NC, p=0.62). In group C, 36% (84/231) of patients underwent surgery within 72 hours of cancellation, 47% (110/231) of procedures were rescheduled, and 6.9% (16/231) were not performed. 30.7% (71/231) were potentially preventable. All cancelled patients were asked to complete the survey; 43.7% (101/231) responded, with 22.8% (23/101) describing feeling upset. However, 92.1% (93/101) felt the cancellation was justified. Conclusion This single institutional study suggests a relatively high number of planned same-day surgeries are being cancelled. A third of these may be preventable. Despite this, patients were understanding. Actions to decrease cancellations should be identified to improve efficiency.