We report a case of fatal cardiovascular collapse that occurred during Ethanol sclerotherapy of a venous malformation in a 21-year-old woman. The malformation was located on the anterior part of the thigh. Fifty ml of a mixture of Ethanol, Ethibloc and Lipiodol containing 35 ml of Ethanol (0.52 ml/kg) were injected under fluoroscopy. A major drop in arterial pressure was recorded after release of the tourniquet placed at the thigh root. The patient died after four hours of intensive cardiac reanimation. Her blood alcohol level was 0.4 g/l one hour after the end of the intervention. The cardiac toxicity of ethanol depends more on the potential acute venous contamination than on the blood alcohol concentration. The currently admitted "safety limit" of 1 ml/kg of bodyweight for ethanol sclerotherapy of venous malformations is certainly unsafe and must be redefined.