Aim: The aim of this study was to compare the effects of bevacizumab and ranibizumab on visual function and macular thickness in patients with diabetic macular edema (DME). Methods: The data of diabetic patients who had been treated with bevacizumab for DME were reviewed. Those patients who received 1 injection of intravitreal bevacizumab and ranibizumab with at least 6-month interval were considered for enrollment. The best-corrected visual acuity (BCVA) assesment with Early Treatment Diabetic Retinopathy Study (ETDRS) chart and central subfield macular thickness (CSMT) measurement using optical coherence tomography-3 before and after the injections were recorded as outcome measures. Results: The study included 29 eyes of 29 patients with a mean age of 56.18±13.07 years. The median BCVA was 59 ETDRS letters and the median CSMT was 411 μm preceeding the bevacizumab injection. At the 4th-6th week control after the injection, median BCVA increased to 61.50 ETDRS letters and the median CSMT decreased to 373 μm. This change in BCVA and CSMT was found to be statistically significant (P=0.029 and P=0.011, respectively). The mean interval between bevacizumab and ranibizumab treatment was 9.54±2.64 months. Ranibizumab treatment increased the median BCVA from 53 to 66 ETDRS letters and decreased the median CSMT from 428 μm to a level of 279 μm, which were statistically significant (P<0.001 and P<0.001, respectively). The median change in BCVA was 4.5 ETDRS letters in the bevacizumab group and 6 ETDRS letters in the ranibizumab group (P=0.58), whereas the median changes in CSMT were 41 and 100 μm after bevacizumab and ranibizumab injections, respectively (P=0.005). Conclusions: Bevacizumab and ranibizumab are both effective antivascular endothelial growth factor drugs preferred in the treatment of DME. Our comparison of both therapies on the same patients suggested that the effect on BCVA was not statistically different, but ranibizumab provided more decrease in CSMT. © Copyright 2011, Mary Ann Liebert, Inc.