In order to challenge the immunopotentiation of the acidifier Nutrilac versus vitamin E, 3 replicate laboratory controlled trials were carried out in cy-clophosphamide (CP) immunosuppressed chick-Cns.The immunosupressing effect of CP on cell medi-ated and humoral immunity proved to be effective with severe dramatic effect on serum transferrin (Tf) and immunoglobulins (IgG and IgM). Marked alterations in the morphologic features of major lymphoid organs and their weight / body weight indices were evident. The immunoassay revealed that Nutrilac strongly Sustained the production of anti-sheep red blood cells (SRBCs) hacmagglutinating (HA) antibodics 7 days post immunization till the end of the experiment with a geometric mean ranging be-tween 2.1-5.5. While vitamin E humbly sustained the HA titer at 14 and 2] days post immunization with a geometric mean of only 0.5 for each. Ad-ministration of Nutrilac and vitamin E highly im-proved the level of serum Tf, IgG and IgM during the entire period of the cxperiment. They also significantly increased stimulation indices of lym-phocyte transformation 7-14 days post immuniza-tion with SRBCs till the end of experimental peri-od (21 days) provided that Nutrilac was superior to vitamin E. Bursal / body weight index was significantly increased at 14 and 21 days post treatment with Nutrilac and at 21 days post treat- ment with vitamin E over CP immunosuppressed non-treated control chickens.