Background: The aim of this study is to find the correlation of the glomerular filtration rate (GFR) measured using Gate’s method and modified Modification of Diet in Renal Disease (mMDRD) equation. Materials and Methods: Patients who received Tc-99 DTPA renal scintigraphy were enrolled in the study. The GFR obtained from Gate’s method via renal scintigraphy and mMDRD equation from plasma creatinine were recorded. A comparison and correlation between the GFRs based on different time intervals was analyzed.  Results: Sixty patients were enrolled in this study. They were divided into four groups based on different time intervals between radionuclide renal scintigraphy and plasma creatinine test. Group 1, 2, 3, and 4 consisted of patients whose plasma creatinine tests checked within ± 3 days, ± 4–7 days, ± 8–14 days, and ± 15–31 days from renal scintigraphy, respectively. Correlation coefficient of group 1, 2, 3, and 4 showed 0.87 (p < 0.001), 0.79 (p = 0.007), 0.67 (p = 0.009), and 0.58 (p = 0.012), respectively. Conclusion: Significant correlations were noticed in the GFR calculated from Gate’s method and by mMDRD equation. It was found that the shorter the time interval between plasma creatinine test and radionuclide renal scintigraphy, the higher the correlation was.