The aim of this article is to review various methods used and started to introduce into practice for determining platelet function, their possibilities, advantages, and disadvantages. Nowadays, in platelet function investigations, devices and their systems with unequal possibilities, operating in different principles, are used. However, because of a wide variety of platelets defects, none of them gives the accuracy of 100%. In order to avoid mistakes, several assays are used. Analysis of platelets function testing is represented in two ways: according to its investigation object and investigation methods and according to the most frequently used platelet function assays. The most important criteria are presented in two different tables.