Studies show that people with a high level of irrational beliefs tend to develop emotional problems. The purpose of this study was to investigate if irrational beliefs (demandingness, awfulizing, frustration intolerance and self-downing), perceived self-efficacy, patient age and surgical condition severity are predictors of preoperative anxiety, depression and distress. A total of 40 patients admitted to the Surgery Unit of the County Clinical Hospital Cluj-Napoca, Romania, were evaluated between February and June 2017. The results of the study show that age is the most important predictor, explaining 13.6% of the preoperative anxiety variance, 17.4 % of the preoperative depression variance and 14.2% of the preoperative dysfunctional distress variance. Overall irrationality has explained 11% of preoperative anxiety variance, 11.1% of preoperative depression and 7.4% of preoperative dysfunctional distress variance, while surgical condition severity has proven to be a significant predictor only for the preoperative dysfunctional distress, explaining 22.3% of this variance. [ABSTRACT FROM AUTHOR]