Fatigue caused by cyclic loading is one of the main reasons for gear tooth failure. In areas with high stress concentration, such as gear tooth root, cracks can develop and further spreading of those cracks can result in the final fracture of gear tooth, which can have catastrophic consequences on the machine. One of the methods used for testing load capacity of gear tooth root is the single-tooth fatigue test. This type of test allows collecting fatigue data in high-cycle field of loading in a fast and economically efficient manner under controlled laboratory conditions. The introduction of this paper gives a brief overview of the main causes of gear tooth failures in general, along with the most common types of gear tooth failures. Furthermore, several methods for testing gear teeth via cyclic bending test are described. The three-point load application and the SAE method of testing will be examined in more details. Focus of this paper lies in the effect of friction on the results of single-tooth bending fatigue tests performed by abovementioned methods. It will be primary to consider the effect of friction on the gear tooth root stress. The analysis of these methods will be carried out using the finite element method, with the help of Abaqus 6.13-1 software package. At the very end of the paper, the results obtained from previous analyses will be presented along with the conclusions drawn from them.