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A series of well-known orthostatic tests were performed in order to substantiate complaints of patients in respect to blood volume drawn into both legs as an early orthostatic regulation. It could be shown that the blood volume pooled in the legs changed highly from test to test up to 250%. There was evidence that with increasing stagnating blood volume, there was not only an increase of arterial blood influx to the lower extremities, but a maximum of heart rate as well as reaction to the orthostatic stress. Under standardized conditions, 14 orthostatically unstable subjects have been tested. 57% of them collapsed in the course of the tests. Following a 14-day administration of dihydroergotamine, the percentage of collapsing subjects was reduced to 7%. At the same time there was a decrease in the following simultaneously measured circulatory parameters as heart rate, mean arterial pressure and heart volume, especially in cases where these changes of parameters were significantly high at the beginning of the experiment. Suggestions are given when it is necessary to detect disturbance of early orthostatic regulation in patients subjected to orthostatic tests. The importance of the dicroty quotient of the arterial pulse as a diagnostic criterion is emphasized.