To the Editor: The study by Whitley et al. (Oct. 14 issue)1 concerning early vidarabine therapy to control the complications of herpes zoster brings hope and promise to patients with malignant disease in whom zoster develops as a complication of their underlying illness. The results of this study must be interpreted with caution, however, since many of the patients were receiving corticosteroids and cytotoxic chemotherapy. The effects of these drugs may have influenced the final conclusions regarding the efficacy of vidarabine in preventing post-herpetic pain and dissemination. Corticosteroids appear to be of benefit in preventing post-herpetic pain. In a. © 1983, Massachusetts Medical Society. All rights reserved.