Intravenous diazepamwas evaluated as a preoperative medication prior to periodontal surgery. Ten patients were subjected to two separately scheduled surgical episodes. During one procedure, a placebo was administered via an intravenous drip and during the other procedure, diazepam was titrated until Verrill's sign was reached. Vital signs, skin temperature, galvanic skin response, and serum cortisol were monitored and analyzed during both procedures. Vital functions were more stable in diazepam‐sedated patients than in the placebo group. This was manifested by less increase in systolic blood pressure, respiration and heart rate. The galvanic skin resistance was increased and serum cortisol values decreased throughout the sedation phase, suggesting a reduced sympathetic arousal. This study indicates that intravenous diazepam sedation enhances patient comfort and improves physiologic safety during periodontal surgery.