At present there are no topical otological preparations on the World Health Organisation's essential drug list, largely due to the ototoxic potential of preparations containing aminoglycoside antibiotics. Acetic acid and Burow's solution have long been used in the treatment of the discharging ear. The aim of this study was to ascertain the antibacterial activity of these two preparations against the most commonly occurring bacteria isolated from discharging ears in our department. Twenty fresh isolates of each of the following organisms--Pseudomonas aeruginosa, Staphylococcus aureus, Proteus mirabilis and Streptococcus pyogenes--were plated onto blood agar and tested against one per cent, two per cent and three per cent acetic acid and Burow's solution (13 per cent aluminium acetate). The activity of each agent was ascertained by the size of the zone of inhibition of bacterial growth. Burow's solution showed significantly larger average zones of inhibition than acetic acid (p < 0.001). The two per cent and three per cent acetic acid as well as the Burow's solution were active against all the organisms tested.