Abstract. The phtalate induced modifications on osteoblastic cells have been monitored in a model system in vitro: preliminary encouraging results, independently obtained by calorimetry (DSC), confocal laser scanning microscopy (CLSM) and coupled gas chromatography-mass spectrometry (GC-MS), show the possibility to relate kinetic data and immunofluorescence images, that are very useful to show the entry and the localization of phtalate into the cells. The calorimetric data were obtained by a cellular living system growth and reacting into the aluminium pans.Key words. Butyl benzyl phtalate -rat osteoblasts -CLSM -DSC -GC-MS.