Twenty-two patients underwent partial or complete ethmoidectomies and were subjected to standardized postoperative follow-ups including endoscopic photography of healing tissues. Sequential biopsies were also taken from the regenerating mucosa and compared with endoscopic findings. On this basis wound healing could be divided into four different phases, allowing for the diagnosis of healing disturbances and clinical planning of stage-dependent therapy. Additionally, a model of wound healing in the maxillary antrum of the rabbit was developed for better understanding the clinical observations. Regeneration of standardized mucosal defects was studied with three-dimensional histomorphological analysis. Circular wounds were found to regenerate concentrically, with wound closure starting by epithelial migration. Within 120 h, granulation tissue covering the wound surface started to become hyperplastic and bone apposition occurred with the formation of osteoid. The systemic application of prednisolone (2 mg/kg per day i.m.) and topical 5% dexpanthenol ointment resulted in an acceleration of late epithelial wound closure together with a reduction in hyperplastic granulation tissue. Local applications of "epidermal growth factor" had no significant effect.