The purpose of this study was to determine the role of intravenous immunoglobulin (IVIG) administration in preterm neonates with S. typhimurium infection. A randomized trial of 47 preterm neonates with intestinal or extraintestinal S. tymphimurium infection was performed. Neonates were randomly divided into two groups: 22 neonates were only given cefoperazone (group 1); 25 neonates were given cefoperazone plus IVIG (group 2). IVIG was given at a dose of 500 mg/kg on da)is 1, 2, 3, and 8 after entry into the study. Following treatment, bacteremia, complications, mortality rate, recovery time, and duration of antimicrobial therapy were evaluated in two groups. Bacteremia was found in 31.4% in group 1 and 8% in group 2 (P<.05); complications developed in 81.8% in group 1 and 16% in group 2 (P<0.01); mortality was 40.9% in group 1 and 12% in group 2 (P<.05). Recovery took 15 days in group 1 and 8 days in group 2 (P<.01). The duration of antimicrobial therapy was 20 days in group 1 and 1 1 days in group 2 (P<.01). We conclude that IVIG treatment in combination with antibiotics in preterm neonates with S. typhimurium infection reduces the complications, mortality rate, and duration of therapy.