Transfer factor (TF) was prepared from buffy coats obtained from 493 units of blood taken from healthy donors, including individuals convalescent from various viral infections. It was administered to 22 of 47 patients with Hodgkin's disease undergoing treatment and consenting to take part in this randomized study to determine if TF would enhance their immunity and/or reduce the incidence of subsequent infections. Skin test reactivity was markedly enhanced in those patients receiving TF as opposed to placebo but other immunological assessments showed no significant differences between the groups. TF was not shown to be of benefit in the prevention of infections (including varicella/zoster).