PTT and systolic blood pressure were measured 20 times at rest and 10 times with Valsalva's Maneuvre from each of five subjects. Linear correlation coefficients (LCs) were calculated from the data obtained only at rest and from both measuring conditions combined. The results showed that LCs from the combined data were highly negative (--0.428-- --0.854) in all five subjects but LCs from rest alone did not show any significant trend in three subjects. It was concluded that PTT did not highly correlate with arterial blood pressure within its spontaneous variation and, therefore, it called the utility of PTT as a target response in blood pressure biofeedback in question.