Background: Generally, the electrolyte abnormalities are seen in many hospitalized patients, and this problem increases in ones with heart diseases. The purpose of this study is determination of the prevalence of electrolyte abnormalities during the coronary artery bypass surgery (CABG) and detecting the relationship between these abnormalities with the complications after the surgeries. Materials and Methods: This is a cross-sectional study, which is done in Chamran hospital, the medical and educational center of Isfahan, Iran, in 2011. The target population included the patients who have undergone CABG in this hospital. In this study, 100 patients who had been candidates for CABG were selected, and we extracted their recorded intra-operative electrolyte information. The collected data was entered into the computer and analyzed by SPSS software. The Chi-square and t student tests were used for data analysis. Results: The mean ± SD of sodium during CABG was 137.95 ± 4.6 (range 127-152) mg\dl. Also, the mean ± SD of potassium was 4.65 ± 0.9 (range: 2.9-7.4). According to these results, 48 patients (48% of all) had electrolyte imbalance and 52 patients (52% of all) were normal. Sodium level in 71% of patients was normal, and in 29% of them was abnormal. Potassium level in 73% of individuals was normal, and in 27% of them was abnormal. Conclusion: Giving an attention to electrolyte abnormalities in patients who have undergone CABG surgery is a considerable necessity for them, and sufficient arrangements are needed to prevent such abnormalities.