Objectives: The aim of this study was to examine whether preoperative risk factors (comorbidities) are associated with fatal outcome in adult cardiac surgery patients. Study design: A cross-sectional study with historical data. Participants and methods: The study included patients operated at the Department of Cardiac Surgery of the University Hospital Center Osijek from October 2007 to October 2019. Participants were divided into two groups. The first group consisted of patients operated at the Department of Cardiac Surgery with a positive outcome. The second group consisted of patients with a fatal outcome during or after surgery and before being discharged from the ward. Patient data were collected from the medical history and operative lists. Results: Out of the total number of participants, 77.48% were men and 22.52% were women. The median age of the surviving patients was 66, and the deceased 68. The median EuroSCORE value of the deceased subjects was 7, while in the surviving patients it was 3. The most common comorbidities include arterial hypertension and diabetes. There is no difference between the groups in coronary surgery. There is a difference between the groups in patients undergoing valvular surgery. Mortality rate is significantly higher in of patients undergoing emergency procedures and re-surgery. Conclusion: Gender and EuroSCORE value are associated with fatal outcome. Also, valvular surgery and aortic surgery have been shown to be fatal for a significant number of patients.