The authors are dealing with the influence of meteorological factors on vascular diseases, primarily on patients with cerebro-vascular disturbances. The parameters mentioned in some studies are also presented in the introduction. There are still few studies by means of which it can be enlightened what happens in the human body affected by atmospheric disturbances. Therefore the basic intention of this study was to come up with answers to at least some segments of this complex problem. A group of patients with cerebrovascular symptoms and signs was chosen for examination. Tests were carried out during cold and warm front passages in anticyclonal situations and low gradient pressure fields within 47 days. In the first stage the tests were carried out only in one day and later for three consecutive days. Meteorological reports are given too. As for medical parameters, the following were controlled: the neurology status, blood pressure, blood test, ECG, REG. The coagulum was regularly checked. The examination was carried out in 12 male and 14 female patients, the age range 43-78. On the basis of the tests, the authors concluded that the most significant changes were noticed in the coagulum and thromboelastogram. According to the results, these changes are manifested during the cold front and during the cold spell caused by it. The findings point to a significant increasing of the thrombocyte aggregation and partly the aggregation index, which can be clinically manifested as the patient's health aggravation. Although other parameters of coagulation did not show significant changes, it cannot be deduced whether they are susceptible to the circumstances in the atmosphere or not.(ABSTRACT TRUNCATED AT 250 WORDS)