The safety and efficacy of PGG-glucan in surgical patients at high risk for postoperative infection who underwent major thoracic or abdominal surgery were determined. Recent studies have reported a 25% to 27% infectious complication rate in patients undergoing major surgery with an average cost per infected patient of $12,000. The efficacy of PGG-glucan pretreatment in prevention of sepsis has been demonstrated in rodent models for gram-negative and gram-positive bacterial and yeast infections. In vitro studies have demonstrated enhanced microbial killing by monocytes and neutrophils in healthy volunteers after PGG-glucan administration. Thus, PGG-glucan may play a role in decreasing the infectious complication rate in patients undergoing major surgery. A double-blind, placebo-controlled randomized study was performed in 34 high-risk patients undergoing major abdominal or thoracic surgery. There were no adverse drug experiences associated with PGG-glucan infusion. Patients who received PGG-glucan had significantly fewer infectious complications (3.4 infections per infected patient vs. 1.4 infections per infected patient, p= 0.05), decreased intravenous antibiotic requirement (10.3 days vs. 0.4 days, p= 0.04) and shorter intensive care unit length of stay (3.3 days vs. 0.1 days, p= 0.03). PGG-glucan is safe and appears to be effective in the further reduction of the morbidity and cost of major surgery.