PURPOSE: To compare the results of intravitreal bevacizumab (IVB) injection alone or in combination with intravitreal triamcinolone acetonide (IVT) versus macular laser photocoagulation (MPC) as a primary treatment of diabetic macular edema (DME). DESIGN: Randomized 3-arm clinical trial. PARTICIPANTS: A total of 150 eyes of 129 patients with clinically significant DME and no previous treatment. METHODS: The eyes were randomly assigned to 1 of the 3 study arms: the IVB group, patients who received 1.25 mg IVB (50 eyes); the IVB/IVT group, patients who received 1.25 mg of IVB and 2 mg of IVT (50 eyes); and the MPC group, patients who underwent focal or modified grid laser (50 eyes). Retreatment was performed at 12-week intervals whenever indicated. MAIN OUTCOME MEASURES: Change in best-corrected visual acuity (VA) at week 24. RESULTS: VA changes among the groups were statistically significant at 6 (P<0.001) and 24 (P = 0.012) weeks. The significant treatment effect was demonstrated in the IVB group at all follow-up visits and in the IVB/IVT group at 6 and 12 weeks. VA changes +/- standard deviation at 36 weeks were -0.28+/-0.25, -0.04+/-0.33, and +0.01+/-0.27 logarithm of minimum angle of resolution in the IVB, IVB/IVT, and MPC groups, respectively (P = 0.053). Significant central macular thickness (CMT) reduction was observed in all groups only up to 6 weeks; however, CMT changes were not significant among the groups in all visits. Overall, retreatment was required for 27 eyes up to 36 weeks (14 in the IVB group, 10 in the IVB/IVT group, and 3 in the MPC group). In the IVB group, in which a greater VA improvement was observed, only 1 injection was required in 72% of the cases. VA improvement >2 Snellen lines at 36 weeks was detected in 37%, 25%, and 14.8% of patients in the IVB, IVB/IVT, and MPC groups, respectively. CONCLUSIONS: Intravitreal bevacizumab injection in patients with DME yielded a better visual outcome at 24 weeks compared with macular photocoagulation. A change in CMT beyond the 6-week time point that corresponded to the vision change was not detected. No adjunctive effect of IVT was demonstrated. FINANCIAL DISCLOSURE(S): The author(s) have no proprietary or commercial interest in any materials discussed in this article.