ObjectiveTo evaluate the effectiveness and complications associated with the use of ranibizumab in the treatment of ZoneⅠand ZoneⅡretinopathy of prematurity (ROP). MethodsData from patients of ROP who had received intravitreal ranibizumab (IVR) injections in Peking University People's Hospital for the treatment of ROP from July 2012 to December 2013 were collected. In total, 151 eyes from 85 patients (56 male and 29 female) were analyzed. The mean birth weight was (1438.6±334.5) g (range:790-2280 g), mean gestational age was (30.1±2.0) weeks (range:25-37 weeks), mean age at the time of intervention was (37.0±6.2) gestational weeks (range:32-45 weeks), mean follow-up was (4.9±3.3) months (range:1.4-20.8 months). The main outcome measures were the regression of ROP and the complications that were associated with the IVR injections. ResultsAfter receiving IVR injections, 120 eyes (79.5%) exhibited ROP regression after single injection. Twenty-six eyes (17.2%) required additional laser treatment for ROP regression after the absence of a positive response to the IVR injections. Five eyes (3%) progressed to stage 4 ROP and required vitrectomy to reattach the retinas. Fifty of 120 eyes which were regressed after single IVR had recurrence of ROP and need additional laser or additional IVR. All of the eyes (100.0%) had attached retinas after the various treatments that they received. No notable systemic complications related to the IVR injections were observed. ConclusionsIVR injection seems to be an effective and well-tolerated method to treat ZoneⅠand ZoneⅡROP. Recurrence of ROP is common and long-term follow up may be needed.