· AIM: To evaluate the effectiveness of vitrectomy on eyes with proliferative diabetic retinopathy.· METHODS: 139 eyes of the 93 cases with PDR were undergone vitrectomy and were followed up for 3-24(16.72±8.53;mean±SD)mo.The visual acuity and the factors causing recurrence of operation were analyzed.· RESULTS: The visual acuity were improved in 98 eyes (70.50%) after vitrectomy. The mean postoperative visual acuity were significantly better than the mean preoperative visual acuity. The main reasons for the failure of operation were retinal detachment and maculopathy.· CONCLUSION: These results demonstrated that vitrectomy is generally an effective procedure in treating PDR.