BACKGROUND: Estimated glomerular filtration rate (eGFR) is one of the most important guidelines in deciding the optimal timing of dialysis initiation. In the present study, we calculated the eGFR at the time of hemodialysis (HD) initiation using 5 commonly used equations to relate them with clinical and laboratory characteristics of the patients and to evaluate which of these equations best define the eGFR at HD initiation. METHODS: We retrospectively analyzed 409 end-stage renal disease patients who were newly started on HD treatment in our institution. The eGFR was calculated using the Cockcroft-Gault equation, the Cockcroft-Gault equation corrected for body surface area, the Modification of Diet in Renal Disease (MDRD) equation, the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation, and the Nankivell equation. RESULTS: The mean eGFRs at HD start were significantly different across the equations. The mean eGFR was 7.8 mL/min for the corrected Cockcroft-Gault equation, 7.7 mL/min for the Cockcroft-Gault equation, 6.2 mL/min/1.73 m2 for the MDRD equation, and 5.6 mL/min/1.73 m2 for the CKD-EPI equation. The corrected Cockcroft-Gault, the MDRD, and the CKD-EPI equations were well correlated with all CKD-specific complications including hypertension, anemia, hyperkalemia, metabolic acidosis, hypocalcemia, hyperphosphatemia, and hyperparathyroidism. The mean eGFR calculated by the corrected Cockcroft-Gault equation showed the lowest coefficient of variation among all the equations. CONCLUSIONS: The eGFR at HD initiation are significantly different according to the used eGFR equations, and the corrected Cockcroft-Gault equation may be the best in defining the eGFR at HD initiation.