Thirty-seven patients suffering from vertigo associated with vertebrobasilar insufficiency participated in our prospective, single-center, double-blind, comparative study. Patients were randomly allocated to treatment with placebo; betahistine (12 mg betahistine dimesylate, one tablet three times daily); or the fixed combination of 20 mg cinnarizine and 40 mg dimenhydrinate (one tablet three times daily) for 4 weeks. The primary efficacy end point was the decrease of the mean vertigo score (S(M)), which was based on the patients' assessments of 12 individual vertigo symptoms after 4 weeks of treatment. Patients treated with the fixed combination showed significantly greater reductions of S(M) as compared to patients receiving placebo (p < .001) or the reference therapy betahistine (p < .01). The vestibulospinal parameter lateral sway (Unterberger's test) improved to a significantly greater extent in patients taking the fixed combination as compared to those receiving placebo (p < .001). No serious adverse event was reported in any therapy group. The tolerability of the fixed combination was judged as very good or good by 91% (betahistine, 73%; placebo, 82%). In conclusion, the fixed combination proved to be statistically more effective than the common antivertiginous drug betahistine in reducing vertebrobasilar insufficiency-associated vertigo symptoms.