Translumbar aortic arteriography was carried out in sixteen patients by injecting 77 +/- 16 ml Télébrix 38 (sodium and meglumine ioxitalamate). Cardiac output was measured by thermodilution by means of a Swan-Ganz catheter. Anaesthesia was induced with thiopentone and fentanyl: the patients were under controlled ventilation. Arterial osmolalities at the 15th, 30th, 60th, 120th, 180th and 300th s showed a major increase, statistically significant from the 30th s on. Arterial and mixed venous histamine measured at the same time varied in parallel, showing a significant rise from the 30th s on for the arterial histamine level. The haemodynamic study of 29 injections showed a significant increase in the left and right ventricular systolic work indices, mostly due to an increase in the systolic index. These changes were similar to those seen during isovolaemic haemodilution. Two phenomena were therefore seen after translumbar aortic arteriography: an almost immediate histamine release, followed later by haemodilution.