Background: Erythrocyte glutathione transferase (e-GST) is a non-dialyzable dimeric protein in red cells. It binds and sequesters a variety of small or large toxic compounds. Objective: This study verifies whether e-GST can assess hemodialysis (HD) adequacy in different techniques or is complementary to the Kt/V urea parameter. Patients and Methods: This is a pilot cross-sectional study included 20 end-stage renal diseases (ESRD) patients on conventional HD, 20 ESRD patients on hemodiafiltration (HDF) for at least 6 months, and 20 healthy controls. Serum e-GST was measured for all patients and controls. Results: Serum e-GST can predict inadequate dialysis at cut off value >14 ng/ml with area under curve (AUC) 0.871, sensitivity 95%, specificity 60%, PPV 70.4% and NPV 92.3%. e-GST was significantly high in patients on conventional HD and HDF (mean ±SD 18.35±5.61 ng/ml, 15.20±4.40 ng/ml) respectively compared with control subjects (mean ±SD 2.80±1.36 ng/ml) P-value <0.0001. Post hoc analysis showed a significant difference between control and both conventional HD and HDF patients (P <0.0001, 0.0001) respectively while no significant differences between conventional HD and HDF patients' P-value (0.061). Patients were redistributed according to kt/v. Patients with kt/v ≤1.3 have significantly higher e-GST (mean ±SD 20.05±4.35 ng/ml) compared with kt/v >1.3 (mean ±SD 13.5±3.82 ng/ml) p-value 0.0001. The patients who have elevated e-GST have increased odds of inadequate dialysis (odds ratio: 28.5). In Conventional HD and HDF, e-GST was negatively correlated with kt/v and URR (P<0.0001). Conclusion: Erythrocyte glutathione transferase is a highly sensitive marker for hemodialysis adequacy in different modalities and didn't need any calculations for interpretation.