PURPOSE: The purpose of this study was to evaluate patient safety, in terms of adverse events, alterations in blood pressure or oxygen saturation (SpO2) in two routine sedation procedures, with and without intravenous analgesia. METHODS: Patients referred for surgical removal of mandibular third molars were treated in a randomized, controlled, single-blinded procedure. Eighty-seven men and women, aged 18 to 44 years, were allotted to either of two treatment groups, midazolam + tramadol (M + T) and midazolam + saline (M + S) or to a control group (C), given no sedation. RESULTS: Tramadol at 1 mg/kg body weight resulted in a higher frequency of oxygen desaturation (SpO2 < 90 %) than a placebo (p = 0.002) but had no effect on mean SpO2 at the end point or at the end of surgery. In both the test groups, there was a significant decrease in diastolic blood pressure (p < 0.001) from baseline to the end of surgery. CONCLUSION: The results confirm that pre-emptive intravenous tramadol, administered at 1 mg/kg body weight as an adjunct to midazolam sedation for third molar surgery, offers a safe method. But, it should be noted that our previous study shows that it is not a particularly effective analgesic. Further testing is therefore warranted, using other doses or other drugs, to find a better intravenous protocol for postoperative analgesia, with maximum effect and minimal risk, in outpatient oral and maxillofacial surgery procedures.