In a randomized double blind study, we analyzed the efficacy of IVIG in the infectious complications in patients at high risk of developing sepsis syndrome. Two groups of twenty patients were enrolled, one receiving 250 mg/Kg of IVIG on the first and seventh day after admission and the other receiving sterile saline as placebo. Serum samples were drawn before IVIG administration and 24, 48 and 72 hours afterwards. The same schedule was used for patients treated with placebo. Sera pooled from healthy donors served as controls. On all the samples, opsonic and bactericidal activity as well as C3, total IgG and serum TNF content were tested. IVIG did not significantly affect total IgG and C3 content. Similarly, opsonic and bactericidal activity tested against E. coli 06 :K-, E. coli 0111 and SAC I was not modified ranging within HPS values. Furthermore, IVIG administration did not change the TNF level. A lower incidence of bacteremia in IVIG treated patients was observed.