The effects on dermal repair of moist conditions, achieved by covering excised wounds with the adhesive polyurethane dressing OPSITE, and dry conditions, achieved by exposure to air through dry gauze dressings, were compared in full thickness excised wounds on porcine skin during the period from 1 to 21 d after injury. Quantitative studies were made of changes in the populations of neutrophils, macrophages, fibroblasts, and endothelial cells. The number of inflammatory phase cells (neutrophils and macrophages) decreased more rapidly under moist conditions than under dry conditions. There was also a more rapid increase in the number of proliferative phase cells (fibroblasts and endothelial cells) in the moist wounds; by 5 d after injury 66% of the cells of the granulation tissue of the moist wounds were of this type, compared with only 48% of the cells of equivalent areas of the dry wounds. By 21 d after injury the number of fibroblasts in the granulation tissue of the moist wounds had fallen below that in the dry wounds, suggesting that progress from the proliferative into the remodelling phase of repair was more rapid in the moist wounds. It was concluded that there was an acceleration of the inflammatory and proliferative phases of dermal repair in wounds healing under moist conditions when compared with those healing under dry conditions.