Abstract: The paper'S aim was to compare the antitumor effects of protein A agents (i. e. SPA. SAC and SAW) with those of CP. to confirm the immunoprotective strength, and to look for the approach of raising their immunotherapeutic effects. The results showed that the therapeutic effect of protein A agents injected directly into tumor-bearing animals was similar to those of CP. although they could not be enough to cope with challenge for as high as 10~7 tumor (EAC) cells but thetr therapeutic effects could be significantly enchanced by combination with chemotherapeutic drugs.