Background: The role of anticoagulation or antiplatelet on post vitrectomy vitreous hemorrhage (POVH) in patients with proliferative diabetic retinopathy (PDR) is rarely investigated in small-gauge vitrectomy era. We investigate the relationship between long-term use of those medications and post vitrectomy POVH in a group of PDR patients.Methods: A retrospective cohort study was carried out in a group of PDR patients who underwent small-gauge vitrectomy in our center. The baseline data on diabetes, diabetic complications, anticoagulation or antiplatelet medications, ocular findings, and vitrectomy details were collected. The occurrence of POVH was recorded during the first three-month follow-up. Factors related to POVH were analyzed using logistic analysis.Results: During a median follow-up of 16 weeks, 5% (11/220) patients had persistent vitreous hemorrhage. Among 75 patients on antiplatelet or anticoagulation therapy, 34 patients were on aspirin, 5 were on heparin, 1 was on dabigatran, 15 were on dual antiplatelet therapy, and 7 were on combined therapy. The occurrence of POVH was not different between patients whose previous therapy was adjusted and whose was continued (0/22, 11/53, p=0.06).Factors related to persistent POVH were the use of antiplatelet or anticoagulation agents (5.98, 1.75-20.45, p=0.004), the presence of myocardial revascularization (130.65, 3.53-4834.50, p=0.08), the presence of coronary artery disease (CAD) treated with medicine (56.52, 1.99–1604.06, p=0.018), and younger age (0.86, 0.77-0.96, p=0.012)..Conclusions: We identified long-term use of anticoagulation or antiplatelet medication, the presence of CAD, and younger age as three independent factors related to POVH. In PDR patients on long-term antiplatelet or anticoagulation medications, particular attention should be given to controlling intraoperative bleeding, and follow-up for POVH should be scheduled.