Objective To compare the outcomes of 23-gauge (23-G) and 20-G vitrectomy combined with phacoemulsification and intraocular lens (IOL) implantation for proliferative diabetic retinopathy (PDR) with coexisting cataract. Methods Retrospective case-controlled study. Ninety-one patients (91 eyes) with PDR and coexisting cataract underwent 23-G (group A, 41 eyes) or 20-G (group B, 50 eyes) vitrectomy combined with phacoemulsification and IOL implantation were studied.One day, 1 week, 2 weeks, 1 month, and 3 months after surgery, the main outcome visual acuity (VA) and postoperative complications were measured. Statistical analysis was performed using an independent samples t test, a paired t test and a chi-square test. Results After the mean follow-up period of 17 months, VA improved significantly from 1.569±0.342 to 0.821±0.421 (t=8.99, P＜0.01)and from 1.658±0.312 to 0.834±0.399 (t=11.47, P＜0.01) in group A and group B, respectively. Postoperatively, 33 eyes (80%) were quiet with no chemosis in group A; in contrast, all eyes (100%) in group B showed marked congestion, chemosis, foreign body sensations and overall discomfort.Postoperative transient hypotony occurred in 3 eyes(7%)and 1 eye(2%),and inflammation in the fibrin anterior chamber was seen in 4 eyes(10%)and 14 eyes(28%)in group A and group B,respectively.The difference for the latter was significant(x2=4.75,P＜0.05).Conclusion For the management of PDR with coexisting cataract,23-G vitrectomy combined with phacoemulsification and IOL implantation is safe and effective with a faster recovery and greater comfort than in the combined 20-G vitrectomy.