Arrhythmias are a known complication for heart surgery and are a major cause of morbidity, increased hospital length and higher economic costs. This study was conducted to assess nurses' performance regarding emergency management of arrhythmias post-cardiac surgery at cardiac centers. This is a descriptive cross sectional study hospital based conducted during 2017, included 77 nurses. Data collected using close-ended questionnaire to assess nurses' knowledge and attitude, and an observational checklist to assess nurses' practice. The data was entered into SPSS for windows version (23.0.0) and descriptive and multivariable logistic regression analysis were performed. Statistical level of significance declared at P value< 0.05, and t-test, ANOVA, and chi-square has been used. The data presented in tables and figures. The level of nurses' knowledge toward emergency management of post-cardiac surgery arrhythmias was poor with percent 75.3%, nurses have poor level of practice with percent 57.1%, and nurse's attitude was positive with 84.4% according to the result. P. Value =0.000, there is significant association between qualification level and nurses' knowledge and there is no significant association between duration of experience and nurses' knowledge with P. Value = 0.118. Therefore, there is no significant link between qualification level and the length of nursing P experience. Value = 0.901 and 0.717, respectively. The degree of practice and knowledge are not necessary more efforts to improve knowledge and practice.