Day-of-surgery (DOS) cancellations are a common and frustrating phenomenon for surgical patients globally. They are both costly to health systems and patients, causing inconvenience, decreased productivity, and emotional distress. In Australia, there are only few published literature that have explored DOS cancellations. This study aimed to evaluate the frequency and reasons for DOS cancellations in a South-East Queensland tertiary hospital. Secondly, the study aimed to understand the characteristics of patients who have been cancelled on day of surgery. A retrospective observational design was used to investigate elective day of surgery cancellations over one year, from January to December 2019. Variables collected included patients’ age, gender, ethnicity, socio-demographic status, carer responsibilities, attendance at pre-admission clinic (PAC), American Society of Anaesthesiologists status; surgical specialty; category of surgery; date of placement on elective surgery waitlist; ethnicity; suburb of residence; socio-demographic status derived from postcode, employment status, carer responsibilities for other(s); number of times of failure to attend past appointments; presentation at PAC; referrals to other services such as the pre-anaesthetic assessment nurse, nurse navigator or social worker and indigenous liaison health officer during the surgery planning phase, and reasons for cancellation. Mean and standard deviation were calculated to describe age. Frequencies and percentages were also reported. Over 1 year, 5334 elective surgeries occurred: of these, 412 patients (8%) were affected by DOS cancellations. Hospital-initiated cancellations accounted for 32% (113/412) of total cancellations, including reasons such as patients’ condition, treatment no longer required or surgeons opting not to perform the procedure. The mean age of patients affected by cancellation was 58 years (SD 17.5). Male patients accounted for a greater proportion of cancellations than females (251 versus 161; 61% versus 39%). Almost half of cancellations were patients who were booked as inpatient admissions (47%, 193/412). Cardiothoracic comprised the specialty most affected by DOS cancellations (43%, 177/412 of cancelled patients). By identifying the reasons for cancellation, and the characteristics of patients who are prone to being cancelled on the day of surgery, we have highlighted that DOS cancellations may be preventable in some cases. Further, quality improvement projects or root cause analysis are required to investigate and further address preventable DOS cancellation.