Background: * Malignant mesothelioma is a malignancy arising from the mesothelial cells of the pleura, peritoneum, pericardium, or tunica vaginalis. * Mesothelioma accounts for 0.10% of deaths annually in the United States. Malignant pleural mesothelioma is the most common of these, comprising of 80% of the cases with an annual incidence of about 2,500 in the United States. * The median survival from diagnosis of pleural mesothelioma is approximately 12 months. The majority of patients present with stage III or IV disease with 85-90% of patients considered unresectable at diagnosis. * Peritoneal mesothelioma has a better prognosis than pleural mesothelioma; nevertheless, patients undergoing therapy for peritoneal mesothelioma have few well-studied treatment options due in large part to the rarity of the disease.

Objectives: -To allow sample acquisition for use in the study of mesothelioma.

Eligibility: * All patients age greater than or equal to 2 years with malignant mesothelioma * Must be able and willing to provide informed consent if 18 or over; parent or guardian must be able and willing to provide consent for patients under the age of 18

Design: * Up to 1000 subjects will be enrolled. * Patients will be followed to determine the course of disease and to record any treatment received for mesothelioma. * Patients will undergo sampling of blood, urine, tumor and abnormal body fluids for tissue banking. * Studies which may be performed on banked material include genetic and genomic studies, establishment of cell cultures and immunologic studies.