During CO2 hysteroscopy the intracavitary pressure increases up to 80 mmHg. This can result in a CO2 embolism, especially after injury/lesion of the endometrium. A 49-year-old female Caucasian patient underwent curettage, and the following day while a hysteroscopy was being performed in general anesthesia a CO2 embolism occurred, with bradyarrhythmia, drop of arterial blood pressure, superior vena cava syndrome, metallic heartsound and hypercapnia. It was possible to achieve recompensation of the right heart failure with drug therapy. Other causes (lung embolism, hypoventilation, increased CO2 production, cardiac causes) could be excluded.