To assess the efficacy of flurbiprofen sodium 0.03% at maintaining pupillary dilation during vitreoretinal surgery, we performed a randomized, double-masked, controlled trial of 139 consecutive patients. The mean decrease in pupil size during surgery in patients who received flurbiprofen was 0.9 mm; for patients who did not receive the drug it was 0.8 mm. The type of surgery performed (vitrectomy or scleral buckle), gender, age, lens status, and a history of diabetes or previous intraocular surgery were assessed and the addition of flurbiprofen to routine preoperative dilation did not significantly affect the mean change in pupil size for any of these subgroups. Of the nine patients who developed at least 3 mm of miosis, five received flurbiprofen and four did not. Use of flurbiprofen did not appear to reduce intraoperative miosis during vitreoretinal surgery in a clinically meaningful manner.