The intravascular oxygenator (IVOX) is a new device which is implanted in the vena cava sup. and inf. where it oxygenates the blood and removes CO2. We report on its successful use in a young patient with severe pneumonia. This 21-year-old female was admitted to hospital with acute respiratory distress due to pneumococcal pneumonia and sepsis following chickenpox. Considering the rapidly progressive course with severe hypoxia and shock, PaO2/PaCO2 values of 6.5/6.4 kPa on mechanical ventilation with an FiO2 of 1.0 and a PEEP of 13 mbar, we decided to implant an intravascular oxygenator. Besides rapid improvement of oxygenation, we observed remarkable recovery of cardiovascular function such as an increase in mean arterial pressure and mixed-venous saturation, while the dose of vasopressors could be decreased. The intravascular oxygenator was removed without problems after 29 days of continuous use, when pulmonary function allowed an FiO2 of 0.45. The patient was discharged from the intensive care unit after 99 days in a good neurological and stable cardiovascular state.