40 not selected elderly patients (average age 79.3 years were investigated with a oesophago-gastro-duodenoskopy (OGD). For premedication the patients got 5 mg Diazemuls R and 20 mg Buscopan R i.v. With 30 patients there was taken a blood-gas-analysis before premedication and before fiberendoscopy. ECG-registration was performed before OGD und during OGD with all patients. The premedication led to a reduction of the p02 on an average of 8.9%. The average pO2 did not decrease below the age-related value. In some cases there was a great difference. With a 86-year old woman the pO2 decreased about 25% after premedication and led to a severe hypoxaemiae. Only patients (12.5%) showed a few ventricular extrasystols, there was no serious arrhythmia. After premedication the heart-rate rose over 100 heart-beats per minute up to maximal 37 beats/minute in 9 patients. If a low dose of Diazemuls R is used, there is no need to do the OGD in elderly patients without premedication, However, there should be the possibility to give a patient oxygen via nasal insufflation to prevent severe hypoxaemia which can occur in some cases. In general, monitoring is only necessary for patients with a higher risk.