This study examined the efficacy of lamotrigine in the prevention of migraine aura. Fifty nine patients suffering from migraine with aura received lamotrigine in a controlled three year prospective open study. Treatment response was defined as a reduction of aura frequency each month by at least 50%. Primary endpoint was reached by three quarters of the patients. Lamotrigine significantly reduced both frequency of migraine aura (mean, 1.5 (SD, 0.6) each month before v 0.4 (0.7) after treatment; p < 0.001) and aura duration (mean, 27 (SD, 11) minutes before v 8 (14) after treatment; p < 0.001). Furthermore, more than three quarters of those patients with a reduction of aura symptoms experienced a significant reduction of frequency of migraine attacks (mean, 2.1 (SD, 1.0) each month before v 1.2 (1.1) after treatment; p < 0.001). Lamotrigine was highly effective in reducing migraine aura and migraine attacks. The strong correlation between reduction of aura symptoms and migraine attacks stresses the potential role of aura-like events and possibly cortical spreading depression as a trigger for trigeminal vascular activation, and subsequently the development of migraine headaches.