Background: Little objective information is available on the influence of occlusive dressings on the healing of cutaneous full-thickness wounds. Objective: Our purpose was to examine the effects of three occlusive dressings—two hydrocolloid dressings (Comfeel Ulcer Dressing, Coloplast A/S, Espergærder, Denmark [hydrocolloid dressing A] and DuoDERM; ConvaTec, Princeton, N.J. [hydrocolloid dressing B]) and one polyurethane film dressing (OpSite, Smith & Nephew, Hull, U.K. [film dressing])—on tissue reactions, degree of inflammation, wound contraction, and epithelialization in full-thickness wounds in domestic pigs. Methods: Standardized 20 mm full-thickness punch biopsy wounds were treated for 10 days. Healing was assessed by light microscopy and by planimetry. Results: Material from both hydrocolloid dressings was phagocytosed as indicated by the presence of foam cells in the granulation tissue. Granulomatous tissue reactions around extracellular vacuoles were found in 10 of 12 hydrocolloid dressing B–treated wounds compared with one in hydrocolloid dressing A–treated wounds and in none of the 10 film dressing–treated wounds ( p < 0.0001). Inflammation was significantly ( p < 0.002) more pronounced in hydrocolloid dressing B–treated wounds. The extracellular vacuoles in the hydrocolloid dressing B group contained dressing material as demonstrated by Fourier transform infrared microscopy. There was a tendency ( p < 0.07) towards a delayed entry into the contraction phase with hydrocolloid dressing B, but there was no significant difference in epithelialization between the three dressings. Conclusion: Wound tissue reactions to different hydrocolloid dressings vary depending on composition. The tissue reactions had no significant effect on wound contraction or epithelialization. (J Am Acad Dermatol 1997;36:53-8.)