This study examined the potential utility of monitoring right ventricular dP/dt as a means of detecting imminent vasovagal syncope. To assess this possibility, continuous right ventricular pressure measurements were recorded in nine patients during induction of syncope by head-up tilt testing. Findings indicated that arterial pressure tended to fall prior to drop in heart rate. RV pressure exhibited a significant, but very small, fall during tilt. DP/dt max increased by 15-20% during tilt, then fell by a median of 30% from maximum value beginning about 2 minutes prior to syncope. Thus, further investigation of dP/dt as a potential marker of impending vasovagal syncope is warranted.