A highly sensitive measurement amplifier (BIT device) was constructed in order to detect possible electromagnetic biosignals in the frequency region between 100 Nz and 100 kHz. Even when working with the highest amplification mode of the BIT device, no endogenous electromagnetic biosignals could be detected on the test persons, but only well-known EMG signals. If the BIT device worked in a feedback mode, electromagnetic oscillations beween 1.7 and 2.9 kHz could be generated and oscilloscopically detected; these oscillations are caused by the oscillator system 'BIT - man', depending on the impedance of the human body. Biological effects of the impedance-depending oscillations were investigated in a simple randomized double-blind study. Three anamnestically healthy persons were treated 20 times with their specific oscillations. The physiological effects of this treatment were measured by pulse plethysmography. Nonlinear analysis of the time series indicated significant changes in pulse dynamics of one person. Linear analysis of heart rate variability showed no statistical significance. Our device was only designed for the project described below. It is, therefore, evident that the research results presented in this paper cannot be applied to any of the therapy devices at present on the market.