This review summarises the diagnostics, staging and treatment of thymic epithelial tumours, of which CT is the current primary imaging. The International Association for the Study of Lung Cancer/International Thymic Malignancy Interest Group TNM staging and the WHO histological classifications are described. Surgery done as total thymectomy with video-assisted thoracoscopic surgery in stage I and open sternotomy in larger stages is the primary treatment if possible. Presurgical tumour reduction with chemotherapy and the possibility of adjuvant radiotherapy after R+ resection is described. Radiotherapy or chemotherapy can be considered, if definite surgery is not possible. Relapse is treated after the same principles as primary disease.