Purpose: To compare the treatment outcome of two doses (1.25mg and 2.5mg) intravitreal bevacizumab for DME at Ispahani Islamia eye Institute and Hospital (IIEI&H) Materials and Methods: Hospital based randomized clinical trial, to be carried out on 50 patients presenting to the Retina clinic of Ispahani Islamia Eye Institute and Hospital, and advised intervention following a clinical diagnosis of DME and fulfilling the inclusion criteria. Informed written consent will be obtained from all patients. Ethical approval was obtained from the Ethical Review Committee at IIEI&H Results: The selected 50 patients were randomly divided into two groups. 25 patients for intravitreal Bevacizumab 2.5mg (group A) and 25 patients for intravitreal bevacizumab 1.25mg (group B). Patient were selected in between the ages of 42 to 66 yrs in bevacizumab 2.5mg group. Patient were selected between the ages of 37 to 80 yrs in Bevacizumab 1.25mg group. In Bevacizumab 2.5mg (n=25) group average improvement of VA (in Snellen's test type) in between pre and post injection group was 2.44 lines. In Bevacizumab 1.25 (n=25) group average improvement of VA (in Snellen's test type) in between pre and post injection group was 1.94 lines. In Bevacizumab 2.5mg group pre injection average Central foveal thickness was 495.84,um and after one-month post injection average Central foveal thickness was 350.9,um (so average reduction of CFT 495.84-350.9= 144.94,um). In Bevacizumab 1.25mg group pre injection average Central foveal thickness was 457.88pm and after 1-month post injection average Central foveal thickness was 346.92pm (so average reduction of CFT 457.88-346.92 =110.96,um). Discussion: Intravitreal injection of bevacizumab at doses of both 1.25mg and 2.5 mg appear to be effective in improving BCVA and reducing CMT. A slightly improved outcome (in terms of lines of vision gained and decrease in central foveal thickness) in the 2.5mg group (Group A). Bevacizumab 2.5mg (n=25) group average improvement of VA (in Snellen's test type) in between pre and post injection group was 2.44 lines. In Bevacizumab 1.25 (n=25) group average improvement of VA (in Snellen's test type) in between pre and post injection group was 1.94 lines, and average reduction of CFT was 110.96,um. However, the clinical significance of this slight gain is debatable, therefore no conclusion can be done regarding the superiority of one dosage above another.In both groups, injections were remarkably safe, with no significant complications in either of the treatment groups. Conclusion: Both bevacizumab in a dose of 1.25mg and 2.5mg were effective in a reduction of central foveal thickness, with a slightly improved visual outcome in the 2.5mg group. IOP elevation was slightly higher in the 2.5mg group, but this change was not statistically significant. Although a marginally better outcome was obtained with the 2.5 mg bevacizumab group compared to the 1.25 mg group, the difference was not clinically significant. A clinical trial with a larger population and the complete 3- month initial dosing regimen is needed to determine the accurate dose.