The effects of four days' treatment with topical Maxitrol (neomycin sulphate 3500 IU/mL, polymyxin-B sulphate 6000 IU/mL with dexamethasone 0.1%) were compared with those of Maxidex (dexamethasone 0.1% alone) in a double-masked study in 111 patients with bacterial blepharitis or conjunctivitis, 95 of whom were evaluable for efficacy. The majority of patients (N = 80) had chronic blepharitis. Maxitrol treatment resulted in a significantly greater reduction (90%) in bacterial counts and bacterial eradication (50%) compared with Maxidex (34% and 17% respectively). Maxitrol treatment also produced a significantly greater reduction in conjunctival discharge than did Maxidex, while the treatments were equally effective in alleviating other ocular signs and symptoms. It was concluded that use of a fixed dose combination steroid-antibiotic product was more effective for bacterial control and therapeutic efficacy in the treatment of chronic blepharitis and conjunctivitis patients than treatment with steroid alone. However, in the long-term treatment of chronic blepharitis the well-known toxic problems of neomycin sulphate have to be taken into account.