Microbial wound contamination has been recognized as a cause of autograft skin graft failure. Human cadaver allograft is believed to decrease or control microbial wound contamination, and by its adherence to the wound bed, to indicate a sufficiently low microbial count to allow successful application of autograft. Suboptimal "take" of more fragile cultured skin grafts after removal of adherent allograft led us to reexamine the microbial population of these wound beds. Immediately before autografts were placed, wound beds beneath adherent allograft were biopsied for quantitative microbiologic analysis. Eighty tissue biopsy specimens from 21 patients were examined. No patients had signs of infection or sepsis at the time of biopsy. Fifty-seven percent of all patients had positive cultures beneath adherent allograft skin. Twenty-one percent of all cultures revealed "infected" wound beds (greater than 100,000 colonies per gram), and 30% of all wounds were "colonized" (less than 100,000 colonies per gram). These data suggest that take and vascularization of allograft does not guarantee that a wound bed is free of microbial contamination.