Recently there has been much interest in the use of serum markers for the diagnosis of the disease. The ideal serum marker would be one that is able to offer: 1) early diagnosis, 2) identification of all the subtypes, 3) differentiation of malignant mesothelioma from benign pleural disease and other metastatic pleural malignancies, and 4) be able to track response to therapy and predict survival. As yet no such ideal marker exists, but studies have suggested the use of osteopontin, mesothelin or megakaryocyte potentiating factor in this role.