Abstract: Objective To investigate the mechanism and effect of immunoglobulin as adjuvant therapy for septicemia in premature infants. Methods Total 118 premature infants with septicemia were randomly divided into observation group(n=58) and control group(n=60). Both groups were given conventional anti infection treatment. The observation group was given immunoglobulin on the first day of diagnosis of septicemia,400 mg/kg per day for 3 days. The recovery time of clinical and laboratory index and the mortality rate were compared between the two groups. The serum Ig G level was compared before and after the treatment. Results The clinical recovery in the observation group was quickly as compared with the control group[(6. 93 ±1. 43) d vs.(8. 47 ±2. 13) d,P < 0. 05]. The recovery time of WBC,PLT,RP and PCT of the observation group were all earlier than those of the control group(P < 0. 05). The mortality rate of the observation group was lower than that of the control group(5. 2% vs. 16. 7%,P < 0. 05). In the observation group,the serum Ig G level increased significantly after the treatment(P < 0. 01); in the control group,the Ig G level was not improved after the treatment(P > 0. 05). Conclusion Immunoglobulin can increase the serum Ig G level and enhance the humoral immune function of the premature infants,it is effective as adjuvant therapy for septicemia in premature infants.