In 2011 a research was performed in order to obtain information about the physiological demands of forest work by felling with chain saw, skidding with cable skidder and by mechanical logging with cut to length method. The research objects were located within the GGO Kočevje area in the Abieti-Fagetum vegetation community. The objective of research was to determine the physiological strain of the standard and mechanical logging and to compare the results with valid admissible standards. The physiological strain was determined by measuring the heart rates in four workers: wood cutter, tractor driver, harvester driver and forwarder driver. In addition to the heart rate measuring, a simultaneous time study was conducted, by which the physiological strain of work in individual processes had later been calculated. Various indicators of work difficulty were calculated: average work heart rate, work heart rate, heart rate reserve and modelled eight-our physiological strain. The standard logging has proved to be the more demanding one. The valid admissible work heart rate (the differential between the baseline heart rate and heart rate during the working process) which stands at 35 bpm was exceeded by two workers: the wood cutter (53 bpm) and the tractor driver (42 bpm). The harvester and forwarder driversć work had proved to be less physiologically demanding. The calculated average work heart rate of the harvester driver is 16 bpm and the forwarder driver 9 bpm.