To compare the effect of a single intravitreal injection of triamcinolone acetonide versus three consecutive monthly intravitreal injections of bevacizumab for the treatment of diabetic macular edema (DME). Forty patients treated with a single intravitreal injection of 4 mg triamcinolone acetonide (triamcinolone group) were compared with 40 patients treated with three consecutive monthly intravitreal injections of 1.25 mg bevacizumab (bevacizumab group). The triamcinolone group showed a significant decrease in mean central retinal thickness (CRT) from 472.5 μm ± 120.35 to 374.0 μm ± 152.31 after 3 months (p < 0.001). The bevacizumab group also showed a significant reduction in CRT from 464.5 μm ± 115.3 to 370.0 μm ± 142.31 (p < 0.001). The triamcinolone group displayed an increase in best-corrected visual acuity (BCVA) following a single intravitreal triamcinolone acetonide injection from a mean of +0.70 ± 0.17 logMAR to a mean of +0.54 ± 0.38 logMAR after 3 months (p < 0.05). The bevacizumab group also showed an increase in BCVA following three injections of bevacizumab from a mean of +0.73 ± 0.28 logMAR to a mean of +0.57 ± 0.33 logMAR (p < 0.05). Statistical analysis showed no significant difference between both groups at 3 months. Our study showed that a single intravitreal injection of triamcinolone is as effective as three consecutive monthly intravitreal injections of bevacizumab for treatment of DME with regard to BCVA and CRT measured by optical coherence tomography. Despite the recent popularity of bevacizumab, three injections are no more effective than a single injection of triamcinolone for the treatment of DME.