Among the tests employed to evaluate the bond strength between dentine and dental adhesives (tensile or shear bond strength measurements, marginal leakage measurements) a general accordance on their reliability cannot be found. Calorimetric measurement may be useful in deciding if the adhesion is mechanical or chemical. In this preliminary study, calorimetric measurements have been performed on three adhesive systems commonly employed: Scotchbond, Gluma, Dentin Adhesit. A calorimeter, equipped with reaction vessels which allow the contact between the two reactants after the thermostatisation has been reached, was used. A thermal effect was observed in all cases, greater for Scotchbond and Gluma, poor for Dentin Adhesit. These values are the sum of different contributes of various reaction paths.