AbstractFrom 1955 through 1964, the authors were actively engaged in experimental and clinical studies concerned with intestinal antisepsis, a form of antimicrobial prophylaxis used by the surgeon to lower the high rate of infectious complications following colorectal operations. Controversy has existed regarding the protective action of antibacterial agents and whether such a regimen has significant advantage over simple mechanical cleansing. Animal studies and clinical trials of 50 drugs, drug combinations, and drug dosage schedules are cited in support of intestinal antisepsis. Kanamycin was selected as the intestinal antiseptic of choice on the basis of studies in 967 patients.