The objective of the study is to evaluate the effect of probiotics to reduce the risk of hospital-acquired pneumonia in Pediatric Intensive Care Unit. The study is a double-blinded randomized placebocontrolled study. Patients were evenly and randomly assigned in two groups. The first group was 50 randomly selected patients who formed the placebo group, while the second group was 70 patients selected randomly to form the intervention group that received the probiotic capsules; Lactobacillus rhamnosus strain GG, once a day. The study site was Pediatric Intensive Care Unit in a universityaffiliated children's hospital. Fifteen (30%) patients in the placebo population developed hospitalacquired pneumonia. Of the 15 patients, infections in 22% were caused by Gram-negative organisms. In the intervention group, 10% developed hospital-acquired pneumonia. The causative agents were predominantly Gram-negative organisms (22% Gram-negative vs. 7% Gram-positive; P-value; 0.01). After 72 h of study, significantly higher oral and gastric colonization rates were observed in patients who were given placebo treatment, compared with those given Lactobacilli. The current study is the first to report these higher significant variations. The current study found an influence of probiotic supplementation on the rate of hospital-acquired pneumonia.