Malignant pleural mesothelioma (MPM) remains suffering poor prognosis in spite of recent diagnostic and therapeutic progress. Although there is currently no established evidence, early diagnosis and early intervention may play a key role to improve prognosis of MPM, similarly to other malignancies. As pleural effusion is usually the first clinical sign of MPM, pleural effusion cytology is often the first diagnostic examination to be carried out. Since the sensitivity of pleural effusion cytology is approximately 60%, however, false-negative diagnosis is given to almost half of true MPM patients at this clinical step. One practical way to reduce the number of misdiagnosed MPM is to encourage performing thoracoscopic pleural biopsy unless definitive diagnosis other than MPM is established. There still remain a considerable number of patients with radiological/thoracoscopic T0 MPM who are misdiagnosed with nonspecific pleuritis after a complete investigation including thoracoscopic biopsies. Such patients will turn out to be malignant during follow-up period, although they have the best opportunity for long-term survival if only early therapeutic intervention is given. Currently, we are performing diagnostic total parietal pleurectomy in highly selected patients, who are characterized with strong clinical suspicion, positive pleural effusion cytology but uncertain pathological diagnosis, excellent cardiopulmonary reserve, and with written informed consent for highly invasive diagnostic surgery for pathologically unproven disease.