Haematothorax (or haemothorax) is defined as an accumulation of blood in the pleural cavity. Spontaneous haematothorax is a rare complication of various intrathoracic diseases, especially pneumothorax or benign and malignant neoplasms. In contrast, haematothorax has to be faced regularly after thoracic interventions due to the high number of interventional procedures in the thorax, especially thoracentesis or thoracic drainage. Diagnosis has to be made by means of the clinical picture, sonography and CT scan of the chest. Spontaneous or post-interventional haematothorax might turn out to be an emergency situation requiring immediate interdisciplinary treatment. Depending on the underlying cause, conservative and surgical treatment might be appropriate. However, early video-assisted thoracic surgery is an effective and safe treatment for the management of haematothorax irrespective of the underlying disease.