Usually several noxious physical factors of the environment are established under working conditions. The literature data suggest the possible synergetic effect of some of those factors. No criteria exist so far for the prognostication of the effect from the combined activity of the physical factors. All norm documents are based on the data from their isolated effect. Many studies on the combined effect of the most frequently found unfavourably acting physical factors were carried out during the last several years: vibration and noise, local vibration and cooling microclimate, noise and high air temperature, and recently--radiofrequent electromagnetic fields and noise. The alterations in organism were followed up, both under laboratory conditions and at-work experiments, by physiological (peripheral vascular tone, skin thermometry, vibrosensitivity, audiometry, peripheral vision) and by some immunological indices. Some data are presented in the paper, outlining the character of the combined effect of two or more on-the-job physical factors, some mechanisms of affection as well as recommendations for their complex assessment.