The authors examined the blood coagulation system in the following 3 groups of workers occupationally exposed to noise and vibration: A--those in whom the examination was conducted 7--16 hrs after finishing the work, B--those in whom the examination was conducted at the 3rd or 4th hour of work, and C--those suffering from angioneurosis of the vibration syndrome of II or III period who have not been exposed to vibration for some recent years. These investigations indicated the lack of blood equilibrium tending to hypercoagulability, shortened duration of plasma recalcination, increased elasticity coefficient of mE thromboelastogram coagulation, increased fibrinogen concentration; these changes were most evident in the group with advanced vibration disease and in those in whom the examination was conducted at their working time. Fibrinolysis duration was significantly prolonged during work, and shortened in those with advanced angioneurosis. In the opinion of the authors, those disturbances in the blood equilibrium system may be accounted for by the conformation changes of proteins.