Thoracic frozen section biopsies including lungs, pleura and mediastinum have crucial role in differential diagnosis of solitary lesions of the lungs and mediastinum. There is a significant difference in patient´s therapeutical management, if the patients suffer from lung primary malignant tumour, metastasis or non-malignant lesion. In this review, we summarize the usefulness of frozen section biopsies in thoracic surgery and provide 5-years of experiences with thoracic frozen section biopsies performed at the Department of Pathology and Molecular Medicine of Thomayer Hospital in Prague. Keywords: frozen section - lung - mediastinum.