Abstarct: Due to importance of fatigue phenomenon in the engineering design and unknowing the low cycle fatigue and on the other hand the increasing application of polymeric materials and the limited polymeric material fatigue data, this thesis is investigated the experimental behavior of polymeric material fatigue and ratcheting polyacetal (POM). At first, in order to obtain mechanical properties of polyacetal, simple tension and pressure tests were performed. Then polyacetal was placed under the stress-controlled uniaxial cyclic loadings. Force and displacement information of all cycles data recorded and then by using them, stress and strain were calculated. Finally, specified that the magnitude of ratcheting strain and rate of ratcheting strain is sensitive to applied mean stress and stress amplitude. In fact, reducing the stress amplitude, reduces the rate of ratcheting strain and increases its value. The mentioned material were placed under cyclic loadings strain-controlled uniaxial. Also it’s determined that polyacetal is indicated the softening behavior under the cyclic loading. Using the results of stress-control tests and utilization of the three fatigue approach of stress, strain and energy, fatigue life of this material is analysed. The stress and energy approach have more success in prediction of fatigue life of polyacetal.