In a 40-year-old farmer's wife presenting with fatigue, shortness of breath on exertion and occasional extrasystoles a space-occupying lesion of the mediastinum leading to obstruction of venous return in the superior vena cava was found. Prior to intended surgery the patient suddenly died following cerebral haemorrhage. Actinomycosis of the mediastinum leading to almost complete stenosis of the superior vena cava was found at necropsy.