Allergic conjunctivitis (AC) affects an estimated 20% of the population in the Western world, with a large fraction suffering due to seasonal or perennial allergen exposures. Bepotastine besilate ophthalmic solution (BBOS) 1.5%, a dual-acting histamine (H(1)) receptor antagonist and mast cell stabilizer, is indicated for itching associated with AC. This study was designed to evaluate the efficacy and safety of BBOS 1.5% for reducing ocular itching associated with AC in subjects enrolled in a natural exposure trial. Eligible subjects in a multicenter, double-masked, randomized, parallel-group, placebo-controlled, natural exposure clinical trial were randomly assigned to either BBOS 1.5% or placebo eyedrops on a 1:1 basis and instilled 1 drop of the test agent into both eyes twice daily for 2 weeks. The mean change from baseline in instantaneous and reflective ocular itching scores at the end of 2 weeks of treatment were evaluated based on subject-assessed severity of instantaneous and reflective itching. Subject-reported adverse events (AEs) were also recorded for safety. Treatment with BBOS 1.5% significantly reduced instantaneous and reflective ocular itching scores from baseline compared with placebo over the 2-week study period(p = 0.007 and p = 0.005, respectively). BBOS 1.5% was well tolerated, and AEs were generally transient and mild. This clinical study indicates BBOS 1.5% effectively and safely treated ocular itching in a natural exposure allergy study and is a useful treatment option for the management of ocular itching associated with AC. (ClinicalTrials.gov identifier number: NCT01174823.)