A double-blind, placebo-controlled, cross-over clinical trial was performed to assess the effect of betahistine hydrochloride (Serc) in Ménière's disease. The diagnosis was based on paroxysmal attacks of rotational vertigo, with tinnitus, and a fluctuating sensori-neural deafness, together with the results of auditory and vestigular tests. Twenty-eight patients were admitted to the trial over 3 years. Twenty-two patients completed the trial. In total, they received betahistine 32 mg daily, for a period of 16 weeks, and placebo also for the same length of time, preceded in every case by a 4-week pre-treatment period. Daily symptom score cards were kept. There was a statistically significant improvement in favour of the drug with regard to vertigo, tinnitus and deafness. Vertigo was the most responsive symptom. No adverse reactions were observed.