Current imaging modalities fail to define precisely the extent of disease in MPM and are inaccurate in selecting patients for treatment. Previous studies have shown that CT and MRI provide anatomical information that is often imprecise in the preoperative staging of MPM. Consequently, about 25% of patients are found to have unresectable tumor at the time of exploratory thoracotomy. PET is now widely recognized as an important staging modality in many cancers, and PET SUV is reported as a prognostic indicator in several malignancies. However, only a few previous studies have investigated the utility of FDG PET scan in MPM. From 1998 to 2003, 65 patients with MPM underwent PET scans. Median PET SUV in the primary tumor was 6.6 (range, 2-23). The median follow-up for all surviving patients was 16 months. Median survivals were 14 and 24 months for the high and low SUV groups, respectively. In a multivariable analysis, high SUV tumors were associated with a 3.3 times greater risk of death than low SUV tumors (p = 0.03). Mixed histology carried a 3.2 times greater risk of death than epithelial histology (p = 0.03). SUV of >4 and mixed histology are poor risk factors in malignant pleural mesothelioma. These findings suggest that FDG-PET can be used to stratify patients for treatment and clinical trials.