Different methods for the determination of the fatigue or endurance limit of metallic materials are commonly used. They provide different results and it is not possible to know a priori which is more accurate. We tested numerically a number of these methods by means of Monte Carlo simulation, so that it was possible to compare the result to the known exact value. We performed uniaxial fatigue testing as well on a steel containing nonmetallic inclusions in two different states (annealed and hardened) and on a cast aluminum alloy, and we found the fatigue limit according to the methods considered. The results obtained confirmed that in cases of materials containing inclusions or voids the application of the methods analyzed could give inaccurate results.