Objectives: Currently, enhanced computed tomography (CT) using a contrast agent is one of the important diagnostic tools, but it can cause radiocontrast-induced nephropathy (RCIN). However, the relationship between the occurrence of RCIN and changes in estimated glomerular filtration rate (eGFR) level in long term follow up is not well known. Methods: We conducted a single center, retrospective study and enrolled 2,057 patients who underwent enhanced CT from January 2010 to December 2020. All contrast agents were low-osmolar materials and were administered intravenously to patients. Diagnosis of RCIN was confirmed by a nephrologist. Those who could be followed up for at least 12 months and those whose annual eGFR change did not exceed 60 mL/min/1.73 m2  were selected in both RCIN and non-RCIN groups. Results: In our study, a total of 2,057 patients were analyzed, and 326 patients(15.8%) were diagnosed with RCIN. By referring to the follow-up period and eGFR change values, 124(38%) patients were identified. They had an average annual eGFR reduction rate of -10.6 mL/min/1.73 m2 (p<0.001). Of the 1731 patients who did not develop RCIN, 714(41.2%) patients had follow-up period of less than 12 months and an annual eGFR change of 60 mL/min/1.73 m2 or more, so they were excluded. Other 1017(58.8%) patients were analyzed and their mean annual eGFR reduction rate was -1.48 mL/min/1.73 m2 (p<0.001). Conclusions: The annual eGFR reduction rates were significantly higher in patients with RCIN than in the patients without RCIN. Therefore, close monitoring is needed after the occurence of RCIN.