Eosinophils can influence fibroblasts and the extracellular matrix in vitro and can participate in tissue remodelling in vivo. Therefore; we analysed the expression of eosinophils and mastocytes in healing laser excisions and control excisions made by scalpel. Carbon dioxide (CO(2)) laser (continuous wave, 5 W) or scalpel excision wounds were created in the dorsal tongue mucosa of 96 rats. Sixteen additional rats were kept as untreated controls. Specimens from the tongues were cut at 16 different healing time points and fixed in 10% formalin. Histological staining with slow Giemsa was done to determine microscopically the eosinophils and mastocytes. Mastocytes were always present, especially in large numbers around blood vessels, in scalpel and in laser wounds. The maximum number of eosinophils was almost two times higher in scalpel excisions than in laser excisions. The peak value was reached after 6 days in laser wounds and after 3 days in scalpel wounds. The increase reverted to normal levels after 10 days in laser wounds and after 6 days in scalpel wounds. The appearance and disappearance of eosinophils was slower in laser wounds. Mastocytes were always present in both groups. This identification as a potential source of transforming growth factor (TGF) alpha and TGF beta clearly permits a role for the eosinophils and influences epithelial cell proliferation, angiogenesis and organization of the wound.