Placental peptide(PP), which was extracted from the placenta of healthy women, was an immunomoderator. It had similar properties as transfer factor(TF) in physiochemistry, bioactivity and immuno-conpetence. This study showed that PP increased the amount of leucocytes and splenic nucleated cells obviously, raised the complement activity, and improved the phagocytosis of phagocytes in the mice. The specific antibody, especially the level of amboceptor antibody of PP treated mice was higher than that of control group, while there was no significant differance between TF group and the control group. It is concluded that PP is superior to TF in promoting the function of humeral immunity and it is a valuable immunomoderator.