Pleural mesotheliomas are uncommon tumors. Correct diagnosis of the benign variant is rarely made preoperatively, and resection is the treatment of choice and is curative. Malignant pleural mesotheliomas are locally aggressive and difficult to treat. They may be seen clinically as localized pleural tumors or as diffuse pleural disease with effusion and encasement of the lung and obliteration of the pleural space. The localized forms of malignant mesotheliomas are fibrosarcomatous. Their diagnosis and treatment do not differ from those for soft-part sarcomas seen elsewhere. Wide en-bloc excision is the treatment of choice and can be curative. The diffuse forms of malignant mesotheliomas are mainly epithelial. Treatment is generally unsatisfactory, and long-term survival is rare. Two surgical approaches are currently available: an extrapleural pneumonectomy and a pleurectomy with irradiation. The authors favor the latter approach because of its wider applicability, lower morbidity rate, and better survival advantage. Steps in selecting the best surgical mode of treatment are presented.