During dental hygiene sessions, systolic and diastolic blood pressure and heart frequency were registered continuously with a finger manometer to investigate the possible cardiovascular effects of root planing/scaling. Ultrasonic subgingival debridement was performed for an average period of 10.6 +/- 2.1 min. Analysis of variance showed significant changes of systolic and diastolic blood pressure, heart rate and the rate pressure product during debridement. The increases in systolic and diastolic blood pressure both correlated significantly with the length of the debridement. After completion of the dental hygiene session, the urinary excretion of adrenaline was increased. The data from this study suggest that painful stimuli during ultrasonic subgingival debridement have extensive cardiovascular effects.