In this study the effect of selective intestinal decontamination of the digestive tract (SDD) on wound colonization was investigated. Ninety-one patients with at least 25 per cent total burned surface area (TBSA) were included in this study. All patients received oral polymyxin. In 63 patients oral co-trimoxazole and amphotericin B were added to the regimen. The addition of co-trimoxazole decreased the incidence of Enterobacteriaceae wound colonization from 71 per cent to 11 per cent (P less than 0.005). Colonization with Proteus was eliminated in patients treated with co-trimoxazole, compared with an incidence of 36 per cent in the group treated with polymyxin alone (P less than 0.001). The addition of amphotericin B decreased yeast colonization of the burn wound from 39 per cent to 10 per cent (P less than 0.005). A close relation was observed between burn wound colonization and colonization of the gastrointestinal tract. No resistant bacterial strains emerged during the period of study. These results suggest that SDD is an effective method for prevention of wound colonization. Further controlled studies are needed to establish the role of SDD in preventing burn wound colonization and wound sepsis.