Twenty-three patients with recurrent Herpes simplex have been treated over a period of 4 years (1969–1972) with poliomyelitis vaccine (Sabin’s), given perorally in the dose of 4 drops once a month for 3 months only. In 74% of cases, this treatment resulted in full recovery with no relapse over a follow-up period of 1–4 years. No harmful side-effects whatsoever were noticed in any of the patients. On the basis of these results, it is concluded that the peroral administration of Sabin’s vaccine is a simple, safe and extremely effective method of treating recurrent Herpes simplex in