PURPOSE: To investigate the short-term effects of panretinal photocoagulation (PRP) combined with an intravitreal injection of Avastin(bevacizumab) as an adjuvant to high-risk proliferative diabetic retinopathy (PDR). METHODS: The data was collected retrospectively from the eyes of high-risk PDR patients, which were divided into two groups. One eye was treated with only PRP (PRP only group) and the fellow eye of same patient was treated with both PRP and intravitreal bevacizumab injection (Adjuvant group). Best corrected visual acuity (BCVA), IOP (intraocular pressure), and new vessel (NV) size in fluorescein angiography were recorded immediately and at the six-week follow-up visit. Adverse events associated with intravitreal injection were investigated. RESULTS: Of 12 patients with high-risk PDR, five were male and seven were female. There were no statistically significant BCVA or IOP changes after treatment in either group (p=0.916, 0.888). The reduction of NV size was found in both groups, but NV size in the adjuvant group showed a greater decrease than that of the PRP only group (p=0.038). Three patients had adverse events after intravitreal injection. Two patients had mild anterior uveitis and one patient had a serious complication of branched retinal artery obstruction (BRAO). CONCLUSIONS: Intravitreal bevacizumab injection with PRP resulted in marked regression of neovascularization compared with PRP alone. One serious side effect, BRAO, was noted in this study. Further studies are needed to determine the effect of repeated intravitreal bevacizumab injections and the proper number of bevacizumab injections as an adjuvant.