In this paper the authors propose an innovative technique to evaluate the integrity state of archaeological discoveries by using thermography. The proposed approach is based on the concept of emissivity. The case study is a marble bust of a woman that dates back to ancient Rome. The emissivity of the bust material has been evaluated by using a standardized procedure. To assess the integrity state of the sculpture, the environment temperature has been kept under control to allow the bust to reach thermal equilibrium. By evaluating pixel by pixel, the temperature deviation around the known equilibrium value, it has been possible to map the emissivity changes in the sculpture due to different conservation or decay states: alveolisation process, erosion, damages, deposition of iron oxide, etc. The proposed approach has allowed us to correlate the changes of emissivity with the integrity state of the sculpture. Preliminary studies on the bust provide interesting information about the deterioration from the original condition.