The clinical efficacy was assessed of a topical antiseptic (aluminium acetate) and a topical antibiotic (gentamicin sulphate) for the initial treatment of otorrhoea. Evidence of resistant organisms developing to either treatments after 9 and 21 days was also examined. 139 affected ears were entered into the trial and of these, 102 (74%) completed the study. Improvement in the otorrhoea occurred in 68% of ears treated with gentamicin and 67% of ears treated with aluminium acetate, with no significant difference between the two treatments. No resistant organisms to aluminium acetate were encountered. Twelve gentamicin-treated ears had gentamicin-resistant organisms at presentation and one patient developed a gentamicin-resistant Pseudomonas during treatment. We therefore recommend a topical antiseptic such as aluminium acetate rather than a topical antibiotic in the initial treatment of otorrhoea on the grounds of cost, avoidance of resistance and toxicity.