Purpose To evaluate histopathologic signs of conjunctival in flammation in patients with conju nctival hyperemia induced by bimatoprost treatment.D esign Prospective interventional study.Methods The s tudy included 15eyes of 15patients scheduled for cataract surgery.Pa-tients in the treatment group(n=9)exhibited trace to moderate conjunctival hyperemia when treated with bi-matoprost 0.03%every day for 15to 30days before surgery.The control group(n=6)included untreated patients with no ocular disease other than cataract.Conjunctival biopsies were obtained for histologic evalu-ation with light microscopy.Result s Vascular congestion was observed in biopsies from 7patie nts(78%)in the bimatoprost group and 5patients(83%)in the control group.Signs of inflammation were fo und in biopsies from2patients(22%)in the bimatoprost group and 2pa-tients(33%)in the control group.Conclusions Histopathologic signs of inflammation were no more fre-quent in conjunctival specimens from bimatoprost-treated patients with trace to moderate hyperemia than in those from untreated control subjects. Purpose To evaluate histopathological signs of conjunctival in flammation in patients with conju nctival hyperemia induced by bimatoprost treatment. D esign Prospective interventional study. Methods The study included 15yes of 15patients scheduled for cataract surgery. Pa-tients in the treatment group (n = 9 ) illustrated trace to moderate conjunctival hyperemia when treated with bi-matoprost 0.03% every day for 15 to 30 days prior to surgery.The control group (n = 6) included untreated patients with no ocular disease other than cataract. Conjunctival biopsies were obtained for histologic evalu- Results with light microscopy. Result s Vascular congestion was observed in biopsies from 7 patients (78%) in the bimatoprost group and 5 patients (83%) in the control group. Signs of inflammation were fo und in biopsies from 2 patients (22%) in the bimatoprost group and 2 pa-tients (33%) in the control group. Conclusions Histopathologic signs of inflammation were no more fre-quent in conjunctival specimens from bimatoprost-treated patients with trace to moderate hyperemia than in from from untreated control subjects.