Cardiovascular diseases occupy a leading place among the causes of death in the population. The main complications of the disease in this group are closely related to changes in the functioning of the hemostasis system, including primary hemostasis. Antiplatelet therapy is used to prevent the development of complications associated with disorders in the hemostasis system. This paper examines the behavior of the platelet population of healthy donors before and after the use of two main types of drugs: acetylsalicylic acid and clopidogrel. Using the method of scanning flow cytometry, the shape index of single platelets was measured, followed by the construction of distributions according to this characteristic for native samples and after exposure to a small amount of an activation agonist. The sensitivity of platelets to the activation agonist is assessed by the change in distributions before and after the application of a short course of therapy. As a result of the assessment, the threshold value for the onset of changes in the shape of platelets and sensitivity increased with the use of acetylsalicylic acid, and decreased with the use of clopidogrel. The demonstrated approach for assessing sensitivity can be useful both in assessing the degree of effectiveness of antiplatelet therapy used and in diagnosing the presence of complications in the course of diseases of the cardiovascular system on the part of primary hemostasis.