OBJECTIVE: To study effects of intravitreal pegaptanib (Macugen) on retinal neovascularization. DESIGN: Retrospective analysis of a randomized clinical trial. PARTICIPANTS, INTERVENTION, AND MAIN OUTCOME MEASURES: Individuals with retinal neovascularization identified from a multicenter, randomized, controlled trial evaluating pegaptanib for treatment of diabetic macular edema, with a best-corrected visual acuity letter score between 68 and 25 (approximate Snellen equivalent between 20/50 and 20/320) and receiving a sham injection or intravitreal pegaptanib (0.3 mg, 1 mg, 3 mg) administered at study entry, week 6, and week 12, with additional injections and/or focal photocoagulation as needed during the ensuing 18 weeks, up to a maximum of 6 pegaptanib/sham therapies, were evaluated. Scatter panretinal photocoagulation before study enrollment was permitted, but not within 6 months of randomization and study entry. Changes in retinal neovascularization were assessed on fundus photographs and fluorescein angiograms graded at a reading center in a masked fashion. RESULTS: Of 172 participants, 19 had retinal neovascularization in the study eye at baseline. Excluding 1 who had scatter photocoagulation 13 days before randomization and 2 with no follow-up photographs, 1 of the remaining 16 subjects had panretinal photocoagulation during study follow-up. Of these 16 subjects, 8 of 13 (62%) in a pegaptanib treatment group (including the one receiving panretinal photocoagulation), 0 of 3 in the sham group, and 0 of 4 fellow (nonstudy) eyes showed either regression of neovascularization on fundus photographs or regression or absence of fluorescein leakage from neovascularization (or both) at 36 weeks. In 3 of 8 with regression, neovascularization progressed at week 52 after cessation of pegaptanib at week 30. CONCLUSIONS: Most subjects with retinal neovascularization at baseline assigned to pegaptanib showed regression of neovascularization by week 36. These findings suggest a direct effect of pegaptanib upon retinal neovascularization in patients with diabetes mellitus.