Introduction. Postoperative atrial fibrillation (POAF) after non-cardiac surgery is common problem. It is associated with subsequent cardiovascular complications and mortality. Currently, there is no data available to assess the risk of POAF and outcomes in patients who are scheduled to undergo non-cardiac surgery. Objective. The purpose of this study was to identify perioperative factors that were associated with the development of AF development in the early postoperative period in patients who died in hospital after performing non-cardiac abdominal surgery. Material and methods. Retrospective cohort study. We analyzed data from 83 patients in the period 2015–2019. The average age was 75 (64; 82), men – 57% and women – 43%. POAF was defined as an AF that was registered on the heart monitor continuously for at least 10 minutes in the early postoperative period. Results. According to the urgency of surgical intervention, in 75% of cases, the operation was performed in an emergency and urgent manner, in 25% of cases – in a planned manner, which meant more thorough preparation and preoperative examination of patients. One-third of the patients were taken for a repeated intervention – relaparotomy. The frequency of POAF was 65% of cases. Pneumonia occurred with the same frequency – 64%, bleeding was in 18% of cases, systemic inflammatory response syndrome (SIRS) – in 40%. When comparing groups of patients who developed POAF and without it, statistically significant differences were found in the frequency of SIRS: 29% in the group with POAF, versus 4% in the group without POAF (p<0.001); and in the frequency of volume intraoperative infusion: 51% in the group with POAF, versus 19% in the group without POAF (p<0.001). Also at the border of significant differences was the frequency of thromboembolic complications: 23% in the group with POAF, versus 6% in the group without it (p=0.055); and the frequency of relaporotomies in the groups: 37% in the group with POAF, versus 17% in the group without it (p=0.080). Perioperative factors associated with POF were determined using multivariate logistic regression. Conclusion. AF is a frequent complication of non-cardiac surgery: in patients who died in the early postoperative period, this heart rhythm disorder was recorded in 2/3 of cases. There were three indicators that were statistically significantly associated with the development of POAF: SIRS, intraoperative infusion of more than 3 liters, and thromboembolic complications.