Abstract： To the editor:It has been known that invasion and metastasis of skin melanoma in situ is a complex multi-step process involving in the interaction between melanoma cells and the adjacent stromal cells and basement membrane (BM).1 Over the years,the process of melanoma invasion from epidermis to dermis was observed using animal models or human cutaneous melanoma lesions removed.2,3As for the deleted human pathological specimens,it is difficult to completely restore invasion system in vitro.However,experimental animal is subjected to a damage or death in animal testing.Behind the animal in vivo,it contains various indefinite factors to influence tumor-cell invasion and migration.With the general enhance on awareness of animal protection,organized and realistic artificial tumor model is an acceptable alternative to animal melanoma research in this field,which is an important progress in observing skin melanoma invasion.Recently in vitro reconstructed melanoma models made by different melanoma cell lines cultured on dermal substitute e.g.collagen matrices were reported to study melanoma invasion.1 For instance,Eves et al4 reported that melanoma cells with invasive growth on acellular dermis expressed gelatinases (MMP-2,MMP-9).However,both invasive behavior of melanoma cells and those proteases activity correlated with the invasion seem wide variations in different melanoma cell lines.4 Hence,more experiments on invasion assay in those models would be required in this field.