Vertigo is frequently associated with migraine, and sometimes it is the cardinal symptom. This type of migraine is called "vestibular migraine", "migrainous vertigo", or "migraine-associated vertigo". Earlier findings on effective prophylactic medication for such migraine attacks and their clinical features are few and insufficient. Our aim was to study the influence of prophylactic therapy on this type of migraine and to specify its clinical features. In a retrospective approach 100 patients (median age 47 years, range 21-72 years) with definite or probable vestibular migraine were divided into two groups: those with (74 patients) and those without drug prophylaxis (26 patients). They were then interviewed by telephone at least 6 months after beginning therapy. All patients receiving medical prophylaxis showed a decrease of duration, intensity, and frequency of episodic vertigo as well as nearly all its associated features (p < 0.01). The group without medical prophylactic therapy showed only a reduction of vertigo intensity. Only 39 % of the 100 patients met the current IHS criteria for a basilar-type migraine. Thus, we propose that a new category--"vestibular migraine"--should be added to the HIS criteria. Furthermore, our data show that prophylactic medication may be effective for treating vestibular migraine and its associated symptoms; therefore, patient's response to medical therapy may provide guidance in the diagnostic process of vestibular migraine.