We investigated the effect of beraprost sodium (BPS) on the Raynaud's phenomenon on 15 patients with systemic sclerosis, 3 with mixed connective tissue disease and 1 with Raynaud's disease, respectively. After 12 weeks of administration of 60 micrograms/d BPS, the duration and the incidence of the Raynaud's symptom were significantly reduced and the dermal temperature on the fingers was found to be elevated. Of the parameters which are known to reflect vascular endothelial damages such as tissue plasminogen activator (t-PA), von Willebrand's factor (vWF) and endothelin, the plasma level of t-PA was significantly reduced by BPS. Furthermore, the capillary loop in the nail bed of the fingers seemed to increase in one patient by the treatment with BPS. These results suggest that BPS has a capacity to repair peripheral vascular damages resulting in the improvement of Raynaud's phenomenon.