In this study the authors used the Haemostatometer, a new instrument to monitor the pattern of hemostatic plug formation that occurs in holes in polyethylene tubing through which nonanticoagulated blood is flowing under standard conditions. The pattern and speed of blood coagulation, subsequent to hemostasis, was also monitored. Simultaneously, the time until expulsion of hemostatic plugs formed was measured and considered as spontaneous thrombolysis time (STT). In 10 healthy volunteers, blood samples were drawn and tested before and ninety minutes after administration of 10 mg oral nifedipine. After nifedipine, the initial phase of primary hemostasis was delayed (p less than 0.05), the clotting time lengthened (p less than 0.01), and the STT shortened (p less than 0.01). The authors conclude that the effect of nifedipine on hemostasis and thrombolysis could contribute to its therapeutic efficacy.