Introduction: End stage renal disease (ESRD) patients undergoing hemodialysis (HD) have higher incidence of diabetic retinopathy (DR) and diabetic macular edema. Optical coherence tomography (OCT) which both diagnoses and quantifies degree of macular edema is gold standard for evaluating macular thickness. Materials and methods: We studied 30 patients, with DR who were treated with hemodialysis for ESRD. All patients underwent OCT examination 30 minutes before and after a hemodialysis session. Blood pressure (BP), weight, serum osmolality, glycemic hemoglobin and albumin levels were measured before and after hemodialysis. Student’s t–test and linear regression analysis test were used to analyze data. SPSS version 21.0 system was used for all statistical analyses and p value <0.05 was accepted as statistically significant. Results: In our study, BCVA failed to change significantly after the HD. Central and average macular thickness decreased by 3.49% and 1.61% respectively, both were statistically significant. Changes in maximum, central and average macular thickness, as well as in total macular volume were found to be significantly affected by changes in serum osmolality (p=0.04, 0.002, 0.02 and 0.03, respectively).We found no significant changes in maximum/average macular thickness with changes in total body weight or in mean arterial pressure after HD. Conclusion: Hemodialysis significantly decreases maximum macular thickness assessed by OCT in chronic renal failure diabetic patients with macular edema with no change in BCVA. Osmolality changes after hemodialysis were significantly associated with macular thickness.