This study examines the effects of batroxobin (a defibrinogating drug) on the peripheral circulatory disturbance of 118 patients with vibration syndrome. In 53 cases, batroxobin was intravenously administered once a day for three successive days in the order of 20, 10, and 5 batroxobin units (BU), and 5 or 10 BU were supplemented every day or every second day, respectively, for four weeks. In these cases, the blood fibrinogen and viscosity decreased. A significant decrement in the vascular resistance of the fingers also occurred after each administration. The other 65 cases were subjected to an intravenous administration of 20 BU initially and an additional 10 BU every 2 d for four weeks. For all of the 118 cases the results of skin temperature measurement, finger plethysmography, and nail compression in conjunction with cold provocation showed statistically significant improvement after the therapy. The transcutaneous partial pressure of oxygen and finger blood flow measured in 22 and 27 cases, respectively, were also significantly improved. A sensation of warmth in the whole body appeared in 70.3% of the 118 cases after the therapy. The results suggest that defibrinogation by batroxobin is useful for improving the peripheral circulatory disturbance of the vibration syndrome.