Malignant pleural mesothelioma is an uncommon, but no longer rare, cancer that is frequently difficult to diagnose and poorly responsive to therapy. Because of the difficulties distinguishing mesothelioma from metastatic adenocarcinoma and reactive pleural inflammation, thoracoscopy or open lung biopsy are usually required to obtain adequate samples for pathologic evaluation. Staging of mesothelioma remains a controversial area. Because none of the six staging systems used in the past was found to be predictive, a TNM-based staging system was recently proposed and is awaiting universal acceptance. Generally perceived as a death sentence, this cancer is associated with a median survival of 9 months from the time of diagnosis in most series, but newer therapeutic strategies show promise for improved and even long-term survival in select cases. Randomized trials are awaited to determine if the improvements in survival reported are not simply due to patient selection.