Objective:  This study included a total 274 participants, including 111 fimasartan and 163 losartan groups from three institutions. Changes in proteinuria 6, 12, 24, and 36 months after fimasartan administration were measured and compared to baseline. At the same time, changes in estimated glomerular filtration rate (eGFR) and blood pressure during the same period were also measured. The same measurement was performed in the losartan group and compared with fimasartan group, respectively. Methods:  In the group administered with fimasartan, proteinuria was significantly decreased at 6 months (27%, P=0.014), 12 months (28%, P=0.017). There was no significant difference in reduction of proteinuria compared to the losartan group. After adjustment, proteinuria decreased at 6 months, 12 months, 36 months, respectively and no difference was found compared with losartan group. The fimasartan group decreased eGFR faster than the losartan group at 12 months, but at other time point, there was no statistical significant difference. Systolic blood pressure (SBP) was reduced at all the time points in both groups after adjustment, but the SBP reduction of two groups had no difference. Results:  In this study, fimasartan showed a comparable effect on proteinuria reduction compared to losartan. Conclusions: Objective:  Fimasartan, one of the angiotensin receptor blockers (ARBs), was approved in 2010 and has been used as the primary treatment in hypertensive patients with chronic kidney disease. However, there are lack of data comparing the effects of fimasartan on reducing proteinuria with other ARBs. Therefore, this study aims to confirm changes in proteinuria in patients with hypertension and diabetic chronic kidney disease who have been administered fimasartan. Methods:  This study included a total 274 participants, including 111 fimasartan and 163 losartan groups from three institutions. Changes in proteinuria 6, 12, 24, and 36 months after fimasartan administration were measured and compared to baseline. At the same time, changes in estimated glomerular filtration rate (eGFR) and blood pressure during the same period were also measured. The same measurement was performed in the losartan group and compared with fimasartan group, respectively. Results:  In the group administered with fimasartan, proteinuria was significantly decreased at 6 months (27%, P=0.014), 12 months (28%, P=0.017). There was no significant difference in reduction of proteinuria compared to the losartan group. After adjustment, proteinuria decreased at 6 months, 12 months, 36 months, respectively and no difference was found compared with losartan group. The fimasartan group decreased eGFR faster than the losartan group at 12 months, but at other time point, there was no statistical significant difference. Systolic blood pressure (SBP) was reduced at all the time points in both groups after adjustment, but the SBP reduction of two groups had no difference. Conclusions:  In this study, fimasartan showed a comparable effect on proteinuria reduction compared to losartan.