Background: Pleural mesothelioma is a very rare neoplasm; especially the local form. The diagnostics is difficult and the prognosis unfavourable. Case Report: We presented a case of a man with dyspnoea and cough. His chest radiogram showed hydrothorax on the left side. Neither the examinations of the pleural liquid, nor the CT-guided fine needle biopsy established the diagnosis. CT showed features suggestive of pleural mesothelioma. The diagnosis was confirmed by thoracoscopy. Although no neoplastic cells were found in the thoracoscopic specimen from the supradiaphragmatic tumor, we assumed that to be a case of a diffuse, primarily local form of mesothelioma. Conclusions: Diagnostics of pleural mesothelioma is very difficult. CT and thoracoscopy seem to be very valuable diagnostic methods. It is worth remembering that pleural mesothelioma can have a local form which may transform into a diffuse one.