Twenty patients with large area granulating wounds were selected for the study. On each patient, a small area of uniform appearance was divided into four subareas, and each subarea was randomly assigned treatment with a single 24 hour application of cadaver allograft, fresh porcine xenograft, formalinized xenograft, or "wet-to-dry" applications of coarse mesh gauze changed three times daily. At 24 hours, all four areas were uncovered. The subareas were ranked in terms of appearance on a best, second best, third best, and worst scale by experienced paramedical personnel who were not told which area received which treatment. Contact sponge quantitative microbiology was performed on each subarea before and after treatment on seventeen of the twenty patients. The results of these rankings suggest that coarse mesh gauze, changed three times daily, was significantly better at improving wound appearance than any of the biologic dressings. Among the biologic dressings, formalinized xenograft was significantly the worst. There was no significant difference between cadaver allograft and porcine xenograft. Analysis of quantitative cultures was limited by the problems of applying statistical methods to series of paired cultures in which initial values are quite different. Within the framework of such limitations and our 24 hour study, there was not significant change in surface colonization when either coarse mesh gauze or biologic dressings were used.