Postoperative complications are common post colorectal surgery and contribute to increased morbidity, mortality, length of stay and healthcare costs. But what else can we do to reduce these complications? The human microbiome interacts with the human host in complex ways. It can both improve the health of the host, as well as reduce the health when dysbiosis is present. Interventions which alter the microbiome including prebiotics, probiotics, and bowel preparation with or without antibiotics may be the newest tools in our arsenal to improve postoperative complications in our patients.