A prospective, randomised, double blind, partial crossover, placebo controlled trial has been conducted to compare the performance of topical fusidic acid gel (Fucithalmic) and oral oxytetracycline as treatment for symptomatic chronic blepharitis. Treatment success was judged both by a reduction in symptoms and clinical examination before and after therapy. Seventy five per cent of patients with blepharitis and associated rosacea were symptomatically improved by fusidic acid gel and 50% by oxytetracycline, but fewer (35%) appeared to benefit from the combination. Patients with chronic blepharitis of other aetiologies did not respond to fusidic acid gel but 25% did benefit from oxytetracycline and 30% from the combination. Our results demonstrate the need to investigate patients with blepharitis for concomitant rosacea as they respond well to targeted therapy.