Malignant mesothelioma (MM) is a highly aggressive, incurable neoplasm associated with asbestos exposure. Early detection of MM is not easy and radiological surveillance is imperfect. The use of blood-based biomarkers might solve this difficulty and allow detection of MM at an early stage when combined treatment involving surgery, chemotherapy and radiotherapy might be effective. In the research project entitled “Comprehensive approach on asbestos-related diseases” supported by the “Special Coordination Funds for Promoting Science and Technology (H18-1-3-3-1)”, we conducted an exploratory study on the detection of markers for diagnosing early-stage MM. In this study, we have shown that serum soluble mesothelin-related peptide (SMRP) is a highly specific and moderately sensitive biomarker for diagnosing MM. SMRP levels in pleural effusion were elevated not only in advanced-stage malignant pleural mesothelioma (MPM), but also in early-stage disease. SMRP in pleural effusion can be an MPM-specific biomarker with greater sensitivity than in serum, especially for the early stage of the disease. Circulating tumor cells (CTCs) and circulating endothelial cells (CECs) were considered to be useful surrogate markers of disease progression in MPM, although the lack of sensitivity for early-stage disease remains to be improved. Cytological analysis with gene expression profiling has been more effective in detecting early-stage MPM with pleural effusion. In conclusion, blood or effusion-based biomarkers, possibly in combination with other new modalities, such as a thoracoscopy combined with the advanced imaging systems consisting of autofluorescence imaging (AFI) and narrow band imaging (NBI), will show some promise for curing MPM if the disease is detected at an early stage.