Supraventricular cardiac arrhythmias are the most common rhythm disturbances in patients fol-lowing thoracic surgery. The purpose of our study was to determine which of the clinical parameters are the most valuable in predicting postoperative atrial fibrillation (AF) after lung surgery. Methods: Retrospective analysis was carried out on 987 patients after noncardiac thoracic surgery to define the prevalence, associated risk factors, and clinical course of post-operative arrhythmias. There were 822 men and 165 women, age 34 to 78 years (mean age: 61 ± 8 years). The patients were divided into two groups depending on the occurrence or absence of supraventricular arrhythmia. Group I consisted of 876 patients who were free from rhythm disturbances. The remaining 111 patients exhibited episodes of supraventricular arrhythmia (29 supraventricular tachycardia; 82 AF). These 111 patients were placed in Group II Preoperative, opera-tive, and postoperative data were reviewed. Statistical analysis was performed. Results:A statistically significant difference was found between the two groups in age, previous history of heart dis-ease, and lung resection, especially pneumonectomy. Conclu-sion: Age, history of prior heart disease, lung resection, and the extent of pulmonary resection are the main risk factors for postoperative supraventricular arrhythmia in patients under-going major thoracic operations