Kaposi's varicelliform eruption (KVE) is characterized by disseminated cutaneous eruptions usually caused by infection with herpes simplex virus (HSV). Kaposi's varicelliform eruption is commonly observed among patients with atopic dermatitis (AD). Why AD patients are prone to HSV infections is still an enigma. Recent findings suggest that an increased number of IL-4-secreting cells can be cloned from lesions of AD. Because IL-4 is a known Th1 cell inhibitor, theoretically, by inhibiting the Th1 cells, it could downregulate the immune response against HSV. In this study, we have evaluated the role of IL-4 on HSV replication.