Gincosan is a combined preparation containing 60 mg ginkgo biloba and 100 mg ginseng, standardized of 24% ginkgo flavone glycosides and 4% ginsenosides. Hemorrheological and circulatory effect as well as blood pressure behavior after the administration of gincosan were studied in an acute trial on 10 voluntary subjects with a mean age of 26 years. Systolic blood pressure decreased significantly both for the large-dose (120 mg ginkgo biloba +200 mg ginseng) and low-dose administration (60 mg ginkgo biloba +100 mg ginseng). Diastolic blood pressure and heart rate decreased only in the high dosage group. The pathologically increased spontaneous platelet aggregation is reduced by both dosages. Erythrocyte velocity in nail fold capillaries increased significantly only in the high dosage group. The parallel group comparison of the high dosage and placebo group showed that they differ only significantly concerning the erythrocyte rigidity, erythrocyte velocity in nail fold capillaries and spontaneous platelet aggregation. A trend towards a decrease in the systolic blood pressure is revealed (p less than 0.1).