Abstract: Red sea bream(Pagrus major)were injected intramuscularly and direct immersion with Vibrio mimicus formalin killed cells)FKC), crude lipopolysaccharide(LPS)preparations and formalinized extracellular toxin(toxoid)of V. mimicus , respectively. The crude LPS prepared by the phenol water method had a little toxicity. The crude LPS was being heated to reduce its toxicity. The effectiveness of vaccination against Vibrio mimicus were evaluated two weeks after the immunization. The results showed that good protections were induced in red sea bream by FKC, LPS and toxoid. After booster immunization, the degrees of protection were enhanced.