Malignant Pleural Mesothelioma is a rare tumour that arise from the mesothelial cells of the pleura and in recent time the incidence of this disease is rising. Because of the implications for management and therapy, it is important to assess the accurate staging. 18F-fluorodeoxiglucose Positron Emission Tomography (18F-FDG PET) is become a useful tool in the diagnosis of many neoplasms, such as Malignant Pleural Mesothelioma. In particular it has been shown to be useful in the evaluation of the extent of pleural disease, in the establishment of lymph node involvement, in the evaluation of tumour invasion into the lung and thoracic wall, in the diagnosis of extrathoracic metastases, in the assessment of the response to treatment, and in planning radiotherapy. Developments in system technology, like improvements in hybrid system (integrated Positron Emission Tomography/Computed Tomography) and the discovery of new radiopharmaceuticals, promise to make PET much more useful and versatile in the future.