Both asbestos and erionite related malignant pleural mesothelioma (MPM) is a serious health problem in Turkey. Erionite has a higher potency in the lung than asbestos and familial clustering of malignant mesothelioma suggests a genetic predisposition to this cancer among affected individuals. Neither Simian virus 40 (SV40) nor human herpes virus 8 (HHV-8) are co-factors in the pathenogenesis of environmentally induced mesothelioma. A survival advantage has been demonstrated in patients with asbestos-induced mesothelioma compared with erionite-induced mesothelioma. This together with the proliferation index (PI) can be used as an independent prognostic factor for patients with malignant pleural. mesothelioma. It is envisaged that the application of these prognostic approaches together with the new TNM staging system will allow investigations to be more precisely carried out and evaluated. (C) 2004 Elsevier Ireland Ltd. All rights reserved.