—Stress is one of the most common reasons for a number of serious diseases. For the prevention and treatment of stress, a psycho-physiological monitoring system for stress measurement is needed. Because of the multifarious influences of stress on the physiological response of the body, a stress measurement system has to take into account as many parameters as possible. The pulse transit time (PTT), which is determined by measuring the ECG and the pulse wave at for example a finger, gives comprehensive information about the cardiovascular system. In a study we investigate the correlation between the PTT and the stress induced by a psychological experiment. We found out that there is a strong correlation and that PTT is an appropriate parameter for stress measurement.