48 patients with a diagnosis of presumptive bacterial conjunctivitis were assessed. They had been treated with either trimethoprim-polymyxin or neomycin-polymyxin-gramicidin eye drops in a randomised double-blind trial. There were 24 patients in each treatment group. There were no significant differences between the two preparations with regard to the eradication of organisms or clinical improvement, and both preparations proved to be very effective. Patient compliance was good and no adverse reactions were encountered with either preparation.