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The purpose of this study was to investigate whether vitreous levels of vascular endothelial growth factor (VEGF) predict late vitreous hemorrhage (VH) after vitrectomy for proliferative diabetic retinopathy, and how VEGF level changes in patients with postoperative late VH.Eighty-five eyes of 68 patients with proliferative diabetic retinopathy who underwent vitrectomy were analyzed retrospectively. Vitreous samples were collected from eyes undergoing primary vitrectomy and from eyes with late VH undergoing second vitrectomy. Vitreous VEGF levels were measured using enzyme-linked immunosorbent assay. The relationship between VEGF level and late VH (>4 weeks) occurring during follow-up as well as clinical findings, and changes in VEGF level in eyes with late VH undergoing second vitrectomy were analyzed.Late VH occurred in 20 (24%) of 85 eyes, and 9 eyes required second vitrectomy. Vitreous levels of VEGF were significantly higher (median: 1,945 pg/mL; P < 0.0001) in eyes with late VH than in those without. Preexisting iris neovascularization (P < 0.0001), hypertension (P = 0.002), and proteinuria (P = 0.040) were also significant risk factors of late VH. Multivariate logistic regression analysis showed that a higher vitreous VEGF level was independently associated with a risk of postoperative late VH in patients with proliferative diabetic retinopathy (odds ratio: 20.8, 95% confidence interval: 2.72–159.47; P = 0.003). Vitreous VEGF level at second vitrectomy in patients with late VH was significantly lower compared with that at primary vitrectomy, but remained elevated (median: 1,610 pg/mL; P = 0.023).In patients with proliferative diabetic retinopathy, high intraocular VEGF level at primary vitrectomy was identified as an independent risk factor of postoperative late VH. Persistent overproduction of intraocular VEGF may be associated with postoperative late VH.