Using the example of an allopathic herbal combined preparation containing Echinacea root, wild indigo root, and white cedar leaf tips (Echinaceae radix + Baptisiae tinctoriae radix + Thujae occidentalis herba = Esberitox N), the efficacy and mode of action of a phytoimmunomodulator, or immune system enhancer, is described. Efficacy of the immunomodulator has been demonstrated in studies of acute viral respiratory tract infections and infections requiring antibiotic therapy. In a recent study compliant to GCP, the therapeutic superiority of the herbal immunomodulator over placebo was confirmed as statistically significant and clinically relevant. The present overview describes a model of the antigen-independent mode of action of phytoimmunomodulation ("immunobalancing").