Background: Renin-angiotensin system blockers (ACE-I or ARBS) is well known to be associated with hyperkalemia in patients with advanced chronic kidney disease (CKD) who are not on dialysis. However, few studies have investigated the relationship between renin-angiotensin system blockers (RASB) and hyperkalemia in chronic HD patients, and the results remain controversial. Methods: The research sample included 111 patients from hemodialysis patients in the hemodialysis division at Tishreen University Hospital in Latakia,Syria .The research sample was divided into two groups : the first group takes RASB and the second group was not taking these medications in order to study the effect of these medication on serum potassium levels .A blood potassium analysis was conducted monthly for 6 months during the time period 2019-2020. Resuls: there was no statistically significant difference in the mean values of serum potassium between the two research groups , but it was lower in the case group.Where the mean values of serum potassium were between the group that was taking RASB and the group

Keywords : Renin-Angiotensin System Blockers , Angiotensin-Converting Enzyme Inhibitor, Angiotensin II Receptor Blocker, Hyperkalemia , Hemodialysis.