Purpose: Bimatoprost 0,03% is a prostamide with a good efficacy like an ocular hypotensive agent. A collateral effect observed using this drug is the presence of hyperemia around 30 to 40 % of the cases. In this study we analysed histopathologically conjunctival segments of patients with hyperemia during the use of bi-matoprost and submited to cataract surgery to evaluate the presence or not of acute inflammatory cells in these cases. Methods: Patients were divided in two groups. Group 1 ( study group) had Purpose: Bimatoprost 0,03% is a prostamide with a good efficacy like an ocular hypotensive agent. A collateral effect observed using this drug is the presence of hyperemia around 30 to 40% of the cases. In this study we analyzed histopathologically conjunctival segments of patients with hyperemia during the use of bi-matoprost and submited to cataract surgery to evaluate the presence or not of acute inflammatory cells in these cases. Methods: Patients were divided in two groups. Group 1 (study group) had