In an open, controlled study, 44 patients complaining of vertigo, dizziness, or both, caused by vascular vestibular disorders were randomly treated with extract of Ginkgo biloba (EGb 761) 80 mg twice daily or with betahistine dihydrochloride (BI) 16 mg twice daily for 3 months. A complete neuro-otologic and equilibrimetric examination was performed at baseline and after 3 months of treatment, with evaluation of clinical findings. In the first month of therapy, vertigo and dizziness improved in 64.7% of patients treated with BI and in 65% of those who received EGb 761. Compared to baseline, no statistically significant changes were observed in cranial scans for patients with a "central" cranial pattern. Likewise, no changes versus baseline were observed in both groups for the equilibrium score. The comprehensive test battery showed the following findings: EGb 761 induced a slight decrease of saccadic delay and considerably increased saccadic velocities; BI improved saccadic accuracy but did not modify delay; EGb 761 improved smooth pursuit gain at 0.4 Hz 40 degrees/s three times more than BI; both drugs asymmetrically reduced nystagmus maximum velocity at 40 degrees/s; both drugs asymmetrically improved the sinusoidal vestibulo-ocular reflex; BI considerably reduced--whereas EGb 761 considerably improved--visuovestibular ocular reflex. No side effects were recorded during the trial except for transient mild headache and gastric upset in 2 patients receiving EGb 761 and transient cyanosis of nails and lips in 1 patient given BI. These results suggest that EGb 761 and BI operate at different equilibrium receptor sites and show that EGb 761 can considerably improve oculomotor and visuovestibular function.