Abstract: Ribavirin is administered to a patient in a dosage range which is effective to modulate lymphokine expression in activated T cells. In particular, ribavirin is used to suppress Th2-mediated T cell responses and promote Th1-mediated T cell response. Thus, instead of administering ribavirin in its well-recognized role as an anti-viral agent, ribavirin is herein used in the treatment of imbalances in lymphokine expression. Such imbalances may be found to be concomitants of allergic atopic disorders such as allergic asthma and atopic dermatitis, helminth infection and leishmaniasis, and various primary and secondary immunodeficiencies, which may or may not also be associated with viral infection.