The analysed factors were characteristics of age, sex, anatomo-pathologic and expression of the immunohistochemical markers. Results: There were 35 malignant pleural mesothelioma and 59 pleural carcinomas were investigated for expression of the following markers: CytokeratinLMW, Thyroid Transcription Factor-1, Surfactant Protein A, Desmin, Mesothelioma Ab-1 and Calretinin.