Background: To evaluate the relationships among vitreous fluid levels of soluble vascular endothelial growth factor receptor-2 (sVEGFR-2), vascular endothelial growth factor (VEGF), and the severity of macular oedema secondary to branch retinal vein occlusion (BRVO). Methods: Twenty-five BRVO patients with macular oedema were enrolled. Vitreous fluid samples were obtained during vitreoretinal surgery to measure the levels of sVEGFR-2 and VEGF. Macular oedema was examined by optical coherence tomography. Results: The vitreous fluid levels of VEGF and sVEGFR-2 were significantly correlated with the severity of macular oedema (ρ = 0.54, p = 0.008 and ρ = 0.40, p = 0.047, respectively). The sVEGFR-2 × VEGF product was also significantly correlated with the severity of macular oedema (ρ = 0.62, p = 0.003). Conclusions: The severity of macular oedema was more closely associated with sVEGFR-2 × VEGF than sVEGFR-2 or VEGF alone, suggesting that macular oedema in BRVO patients may be influenced by both VEGF and sVEGFR-2.