Despite the increasing use of carbon dioxide for endoscopies during the last years, ambient air is still used. The amount of air depends on several factors such as examination time, presumable diameter of the endoscope channel and of course active use of air by the operator. Although endoscopic complications due to ambient air in the gastrointestinal (GI) tract are a rare observation and mostly described in the colon, we report five cases in the upper GI tract due to insufflating large amounts of air through the endoscopes. All 5 patients needed an emergency upper endoscopy for acute presumed upper GI bleeding. In two cases both esophageal variceal bleeding and ulcer bleeding were detected; the fifth case presented with a bleeding due to gastric cancer. Due to insufflation of inadequate amounts of air through the endoscope channel, all patients deteriorated in circulation and ventilation. Two rumenocenteses and consecutively three laparotomies had to be performed in three patients. In the other two, gastroscopies had to be stopped for an emergency computed tomography. All critical incidents were believed to be a consequence of a long-lasting examination with use of too much air. Therefore in emergency situations, endoscopies should be performed with either submersion, low air flow pumps or even better by the use of carbon dioxide.