A cytokinetic study was performed on progressive subcultures of a cellular strain represented by fibroblasts (FG: Fibroblasts Galliera). Our previous studies on these cells showed morphofunctional changes in relation to cell ageing, indicating the stabilization of a cell line with high proliferative capacity. Furthermore, in the present work, we carried out a comparative analysis with a neoplastic strain (SGS/3A cells), characterized by a low state of cell differentiation. The morphological (fluorescence microscopy) and quantitative (flow cytometry) analysis, examined the relative DNA/protein and DNA/RNA ratios. Moreover, the replicative and mitotic activity and the apoptotic degeneration was determined. The results obtained indicated the existence in this biological model of a different relation between cell growth and cell proliferation. The analysis of our results allowed us to hypothesize that the cellular subpopulation selected during the culture progression of FG cells constitutes a cell line highly able of survival in vitro. In these cells the high proliferative activity is opposite to a reduced metabolism.