Potassium is the major intracellular cation with concentrations reaching 120-150 mEq/L. On the contrary, the extracellular fluid potassium concentration is much lower and kept within very narrow levels between 3.5-5.0mEq/L ⁽¹⁾. Aim of the work: this work aimed to assess serum potassium level in patients on regular hemodialysis and to determine its clinical impact on hemodynamic stability during the hemodialysis session. Patient and method: serum (K) level of 30 patients on regular hemodialysis was measured before and after dialysis and the results were correlated with electrocardiographic (ECG) changes. Results: there was no change in P wave, PR interval or QT interval in all the patients, while QRS was found to be shortened in 3 patients (10 %) in the post-dialysis ECG and elongated in one patient (3.3%) in the post dialysis ECG, T wave showed dynamic changes in the form of reduction in the amplitude of T wave in 11 patients (36.7%). Conclusion: the absence of electrocardiographic changes in hyperkalaemic haemodialysis patients should be interpreted with caution.