Objective The aim of the study is to determine the oxidative status in on-pump and off-pump coronary artery surgery and contribute to possible surgical choices in clinical practices in accordance with the information obtained as a result of this study. Methods 52 patients undergoing open heart surgery (26 patients in on-pump group and 26 patients in off-pump group) were included in the study. MDA, GPx, GSH, CAT, and SOD were investigated in blood samples. Results In the on-pump group, it was determined that there were a significant increase in MDA level in the peroperative period compared to the preoperative and postoperative periods and a significant increase in GSH level in the postoperative period than in the preoperative period. Additionally, while there was a significant decrease in CAT activity in the postoperative period than in the peroperative period, there was a statistically significant increase in SOD enzyme activity in the postoperative period compared to the preoperative and peroperative periods. A statistically significant increase was observed in SOD enzyme activity in the postoperative period in on-pump compared to off-pump group. Conclusion It is thought that this oxidative damage can be suppressed by administering a suitable antioxidant supplement in the preoperative and peroperative periods among patients undergoing the on-pump operation.