Although at any time during dental and oral-surgical procedures complications due to the local anaesthetic or general medical condition of the patient may occur, the surveillance of the vital functions is in general restricted to the simple visual contact between operator and patient. The use of monitoring equipment is therefore increasingly encouraged to improve patient safety. In this study we investigated the use of pulsoximetry as a non-invasive and continual surveillance of the arterial oxygen saturation. The study involved 114 patients: the employment of the pulsoximeter showed little difficulty; the SaO2 and the pulse were as a rule accurately ascertained. Monitoring problems were seen in single cases during extreme opening of the mouth and during coagulation. Patient and operator did not feel themselves to be obstructed by the Pulsoximeter. In a total of 14 patients we observed a sudden fall in the SaO2 during the treatment, and in 3 cases a clinically relevant bradycardia. Despite a few application problems, pulsoximetry can be used to improve patient safety.