Abstract A case is reported of a 47-year-old female patient who suffered from massive tumour embolism during a nephrectomy for a renal carcinoma invading the inferior vena cava. Intraoperative monitoring consisted in direct blood pressure measurement (radial artery cannula), central haemodynamic monitoring (Swan-Ganz catheter), pulse oximetry and capnography. During the surgical manipulation of the suprahepatic vena cava, Petco 2 suddenly decreased (from 25 mmHg to 14 mmHg), together with Spo 2 (from 99 % to 89 %), and the mean pulmonary arterial pressure increased from 18 mmHg to 40 mmHg. The drop in arterial blood pressure to 50/30 mmHg, initiated an immediate sternotomy. After clamping the superior and inferior venae cavae, numerous tumour fragments were removed from the pulmonary artery. Cardiac activity restarted after internal cardiac massage, 1 mg adrenaline, 1 g calcium chloride and 150 mmol of molar sodium bicarbonate. The whole procedure lasted 30 min. Arterial blood pressure became stable at 110/50 mmHg, pulmonary arterial and wedge pressures at 20 and 5 mmHg. The Spo 2 increased to 98 %, and Petco 2 to 25 mmHg. The nephrectomy was then carried out, the patient being given 5 μg · kg −1 · min −1 dobutamine and 3 μg · kg −1 · min −1 dopamine. At the end of surgery, systolic blood pressure was 120 mmHg, mean pulmonary arterial pressure 25 mmHg, and Paco 2 34 mmHg. The patient left the intensive care unit after twelve days. After one year of follow-up, no complication had occurred. The value of cardiopulmonary bypass in nephrectomy for renal carcinoma invading the vena cava, or the renal vein, is discussed. Pulse oximetry and capnography helped to make an early diagnosis of tumour embolism ; the usefulness of this type of monitoring is underlined.