Abstract: A method and apparatus for health risk assessment by means of measuring and evaluating the functional state of the mechanisms of physiological adaptation of human organism comprises recording analog signals of heartbeat intervals, filtering the analog signals of heartbeat intervals, converting the analog signals to digital signals of heartbeat intervals, transmitting the digital signals of heartbeat intervals to a central processing unit, detecting R-peaks from the digital signals of heartbeat intervals, measuring time intervals between two consecutive said R-peaks, calculating heartbeat variability parameters from said heartbeat intervals, calculating degree of tension (DT) of regulatory mechanisms and their functional reserve (FR) based on said heartbeat variability parameters, calculating plurality of functional states based on the DT and FR, and calculating posteriori probabilities based on plurality of functional states, wherein probabilities of health risk is determined based on values of DT, FR, at lea