This study was conducted to evaluate the fast improvement, effectiveness & safety of intravitreal injections bevacizumab (Avastin), in different doses, for treating diabetic macular edema (DME). Eyes of 80 patients with diabetic macular edema were randomized and planned to receive three consecutive monthly intravitreal injections of 1.25 mg or 2.5 mg bevacizumab (forty patients for each group). Patients were observed for 4 weeks after 1st injection and the changes in the best-corrected visual acuity (BCVA), central macular thickness (CMT) and adverse events were compared between both groups. CMT was significantly reduced in both groups (P < 0.013). Significant improvements between baseline and 2weeks to 4weeks in the 2.5 mg group, were mean decrease in CMT was 318 t0 182(P<.001), mean BCVA is 0.16 improve to 0.7 and P value 0.001. Intraocular pressure (IOP)measurements post intravitreal (IV) bevacizumab injection was not raised its statistically significant (P < 0.001). CMT improvement with a dose of intravitreal IV injection 2.5 mg is promising a rapid safe effective response for treating DME without any ocular or systemic side effects but Follow-up is still short to make any specific treatment recommendations.