RECURRENT herpes simplex virus (HSV) infections are frequent in patients with the acquired immunodeficiency syndrome (AIDS). Although they are usually self-limiting in the normal host, such infections may produce extensive and persistent ulcerative disease in compromised hosts.1 Several studies have demonstrated the beneficial effects of systemic acyclovir in severe HSV infections in immunodeficient patients, and this drug has become the antiviral agent of choice in the treatment of such infections.2 3 4 5 6 Virtually all HSV strains isolated from patients with acute HSV infections are highly susceptible to acyclovir, but acyclovir-resistant strains have been recovered occasionally from persons who have received prolonged therapy . . .