Objective. To identify risk factors of immediate hypersensitivity reactions and analyze significance of each of these factors in intraoperative immediate hypersensitivity reactions in cardiac surgery. Material and methods. The study included 740 patients who underwent cardiac surgery under general anesthesia. Immediate hypersensitivity reactions occurred in 53 patients. Control group consisted of 687 patients. We evaluated 37 factors, which were considered as potential predictors. Logistic regression was used with calculation of odds ratio (OR), 95% confidence interval (95% CI) and significance level (p) for each factor to determine the prediction model of the development of immediate hypersensitivity reactions. These factors were considered as predictors of immediate hypersensitivity reactions at p-value <0.05. Sensitivity, specificity and significance level were determined for quantitative variables using ROC analysis. Baseline concentration of total immunoglobulin E (IgE) was analyzed in 570 patients to determine predictive value of this parameter for intraoperative immediate hypersensitivity reactions. Results. Risk factors of immediate hypersensitivity reactions are previous allergic events (OR 2.96 (1.68—5.23), p=0.00019), in particular hypersensitivity reactions to food products (OR 4.61 (1.74—12.18), p=0.0021), drugs (OR 3,68; 95% (1,99—6.78); p=0.000035), previous transfusion (OR 3.74 (1.18—11.79), p=0.025), glycemia over 6.2 mmol/l after induction of anesthesia or augmentation of this value by more than 1 mmol/l relative to the preoperative value (p<0.05), intraoperative use of insulin (OR 2.78 (1.53—5.06); p=0.00082). No association of elevated levels of IgE antibodies and other factors analyzed in the study with the occurrence of immediate hypersensitivity reactions was found. The same is true for other factors. Conclusion. Risk factors of intraoperative immediate hypersensitivity reactions are any previous drug (local anesthetics, antibiotics, NSAIDs, etc.) or food allergy, previous transfusions and glycemia over 6.2 mmol/l after induction of anesthesia or an increase in this metabolite of more than 1 mmol/l relative to the preoperative value.