We aimed to evaluate the clinical efficacy of ciprofloxacin plus fluocinolone acetonide (antibiotic plus corticosteroid) ear drops compared to ciprofloxacin (antibiotic) ear drops in diffuse otitis externa. This was a multicentre, randomised, parallel-group, double-blind study involving 590 patients of both sexes aged 7years or older. The rate of clinical cure was higher (p=0.01) with ciprofloxacin plus fluocinolone acetonide than with ciprofloxacin alone. The mean total symptom score was lower with ciprofloxacin plus fluocinolone acetonide (p=0.005). No differences were found in the percentage of patients reporting resolution of otalgia between patients receiving ciprofloxacin plus fluocinolone acetonide and patients receiving only ciprofloxacin. Resolution of oedema and otorrhoea (p=0.003 and p=0.002, respectively) was higher with ciprofloxacin plus fluocinolone acetonide, as was eradication or presumed eradication (p=0.003). There were eight mild adverse events, three with the ciprofloxacin plus fluocinolone acetonide combination (not related to the treatment) and five when ciprofloxacin was administered alone (directly related to the treatment). Ciprofloxacin plus fluocinolone acetonide is a more effective treatment for diffuse otitis externa than ciprofloxacin alone. The ciprofloxacin plus fluocinolone acetonide combination also has an excellent safety profile.