Patients must have AIDS as defined by the CDC, or be patients with other immunocompromised states (transplant patients; other hematologic malignancies with recognized cell-mediated immune deficiency), and have herpes simplex virus (HSV) infection documented by culture and in vitro resistance to acyclovir by standard laboratory susceptibility or suspected resistance to acyclovir after an acyclovir treatment failure in which acyclovir was administered for at least 2 weeks intravenously at doses of 30 mg/kg/day (or a comparative dose adjusted for renal insufficiency). In vitro susceptibility data must be pending in the latter case.