AIM: To evaluate central macular thickness (CMT) and mean choroidal thickness (MCT) in eyes with branch retinal vein occlusion (BRVO), before and after ranibizumab treatment using spectral domain-optical coherence tomography (SD-OCT). METHODS: Forty-two patients with unilateral BRVO and macular edema were included in this study. There were 25 men and 17 women. Using SD-OCT, choroidal thickness was measured at 500 µm intervals up to 1500 µm temporal and nasal to the fovea. MCT was calculated based on the average of the 7 locations. All the eyes with BRVO were treated with intravitreal ranibizumab (0.5 mg/0.05 mL). Comparisons between the BRVO and fellow eyes were analyzed using Mann-Whitney U test. Pre-injection and post-injection measurements were analyzed using Wilcoxon test and repeated measure analysis. RESULTS: At baseline, there was a significant difference between the BRVO and fellow eyes in MCT [BRVO eyes 245 (165-330) µm, fellow eyes 229 (157-327) µm] and CMT [BRVO eyes 463 (266-899) µm, fellow eyes 235 (148-378) µm (P=0.041, 0.0001, respectively)]. Following treatment, CMT [295 (141-558) µm] and MCT [229 (157-329) µm] decreased significantly compared to the baseline measurements (P=0.001, 0.006, respectively). Also BCVA (logMAR) improved significantly (P=0.0001) in the BRVO eyes following treatment. After treatment CMT [BRVO eyes 295 (141-558) µm, fellow eyes 234 (157-351) µm] and MCT [BRVO eyes 229 (157-329) µm, fellow eyes 233 (162-286) µm] values did not reveal any significant difference in BRVO eyes and fellow eyes (P=0.051, 0.824, respectively). CONCLUSION: In eyes with BRVO, CMT and MCT values are greater than the fellow eyes, and decrease significantly following ranibizumab injection.