Purpose: To compare the effects of bevacizumab and ranibizumab on the visual function and macular thickness in the contralateral (untreated) eye of patients with bilateral diabetic macular edema (DME). Materials and Methods: Thirty-nine patients with bilateral DME, who had been treated with both bevacizumab and ranibizumab in the same eye, were considered retrospectively for this study. Recorded outcome measurements included the best-corrected visual acuity (BCVA) assessment with the Early Treatment Diabetic Retinopathy Study (ETDRS) chart and the central subfield macular thickness (CSMT) measurement of the contralateral, uninjected eye before and at 4 weeks after the injections. Results: The median BCVA of the uninjected eye was 50 ETDRS letters and the median CSMT was 459 μm preceding the bevacizumab injection whereas at the control appointment, 4 weeks after the injection, the median BCVA had increased to 52 letters (P = 0.098), and the median CSMT had decreased to 390 μm (P = 0.036). The mean interval between the bevacizumab and ranibizumab treatments was 4.79 1.52 months. The measurements of the untreated eye after the ranibizumab treatment showed that the median BCVA decreased from 55 to 52 letters, and the median CSMT increased from 361 μm to 418 μm (P = 0.148 and P = 0.109, respectively). Conclusions: In contrast to ranibizumab, the intravitreal administration of bevacizumab resulted in a statistically significant decrease in macular thickness in the untreated eye in patients with bilateral DME.