We evaluated 148 patients with allergic conjunctivitis in a double-masked, paired comparison clinical trial comparing ketorolac 0.5% ophthalmic solution with vehicle. Patients received one drop of each study medication in preassigned eyes, four times a day, for seven days. Both treatments showed significant changes from baseline in the signs and symptoms associated with allergic conjunctivitis. Evaluations at the final visit (day 7 or 8) showed that ketorolac-treated eyes had a significant treatment response when compared to vehicle-treated eyes for conjunctival inflammation (p = 0.010), ocular itching (p = 0.006), swollen eyes (p = 0.002), discharge/tearing (p = 0.021), foreign body sensation (p = 0.035), and conjunctival injection (p = 0.016). Mean scores evaluating the overall therapeutic effect of the study treatments at the completion of the study were higher for ketorolac-treated eyes than for vehicle-treated eyes as rated by investigators (p = 0.004) and study patients (p < 0.001). Results of this study confirmed the trends of a previous study showing that ketorolac 0.5% ophthalmic solution applied topically is an effective therapy for allergic conjunctivitis.