We describe therapy with acyclovir in 1 patient with acute meningitis induced by herpes simplex virus type 2 (HSV-2) and in 1 patient with ascending myelitis in connection with meningitis after a primary genital HSV-2 infection. In addition, intermittent or continuous acyclovir prophylaxis against meningitis was employed in 3 patients with recurrent meningitis of probable HSV-2 etiology. Possible beneficial effects of the treatment were seen.