Ten patients with relapsing-remitting multiple sclerosis in acute relapse were treated with a five-day course of intravenous ginkgolide B, a specific inhibitor of PAF-acether. Eight patients had improvement of their neurological score, beginning 2 to 6 days after the initiation of therapy. This improvement was sustained in 5 patients and only transient in 3. Two out of these 3 patients with secondary failure and the other 2 who did not respond to ginkgolide therapy, received i.v. methylprednisolone. Three patients experienced mild side effects under ginkgolide therapy but none of the patients had any serious adverse effect. A controlled randomized study is underway, in order to confirm these results and test higher dosages and more prolonged administration.