In the present study, we have developed an in vitro three-dimensional model to differentiate normal lung cells from lung cancer cells in order to study the mechanisms resulting in lung cancer. Using a reconstituted laminin-rich basement membrane (Matrigel), we were able to culture normal human bronchial epithelial cells and a subset of malignant cells. The two cell types can be readily distinguished by the ability of normal cells to express a structurally and functionally differentiated phenotype within Matrigel. Human bronchial epithelial cells embedded in Matrigel as single cells were able to form multi-cellular spherical colonies with a final size close to that of true acini in situ. Sections of mature spheres revealed a central lumen surrounded by polarised epithelial cells. In contrast, none of malignant cells tested, cell lines and lung biopsies responded to basement membrane by lumen formation. These results demonstrated that this in vitro glandular tumour model can be useful for studies of bronchial oncogene. Indeed, these findings may provide the basis for a rapid assay to discriminate normal human bronchial epithelial cells from their malignant counterparts. In conclusion, the three-dimensional tumour bronchial epithelial acinar-like sphere represents a novel in vitro model to further investigate pathophysiological functions resulting in lung cancer.