Abstract Background and Aims Treatment of Chronic Kidney Disease (CKD) is based on preserving renal functions. Since renal anemia is frequently detected, We use par enteral iron treatments in patients with Chronic Kidney Disease (CKD). However, there are no clear and sufficient studies on the effect of these treatments on the rate of decrease in Glomerular Filtration Rate (GFR). Therefore, we conducted a study comparing the rates of change in renal function in patients who had used parenteral iron for a five years at least. Method Our study is a retrospective cohort study, and 180 patients with CKD (86 women, 94 men, mean age 63.5±11.4 years) who had been followed and treated in Nephrology Outpatient Clinics for at least 5 years and met the study criteria were included into the study. Patients divided into three groups for receiving iron therapy: not received iron therapy, receiving iron carboxy maltose (ICM) and receiving iron sucrose (IS) par enterally . Each group consists of 60 people. The first and last creatinine, GFR values were compared for a 5-year follow-up in each group. Results There was no significant difference between the two groups, those using and not using iron, in terms of creatinine increase and GFR decrease rate. Additionally, no significant difference was detected in the GFR decline rates of patients using ICM and IS. Conclusion We concluded that anemia treatment with iron carboxy maltose and iron sucrose are renally safe in predialysis CKD patients. This study reduces concerns that correction of anemia through parenteral iron therapy in patients with CKD may harm renal function.