SummaryThe tests of platelets adhesiveness to glass are not easily applied to clinical problems, because many factors are involved in this phenomenon and there is lack of agreement between the authors concerning the meaning of these tests. They seem to detect anomalies of the coagulation only and therefore it is not justified to use them to measure the tendency of a patient to bleed, as platelets tend to adhere to sub-endothelial structures and therefore to stop the bleeding. Owing to lack of valid statistical data, it is presently impossible to evaluate if this test is a reliable laboratory guide to determine the propensity to thrombo-embolic complications.