Plastic components in compressors were only used for applications where it was urgent to use them in the past. In the new compressor generation more parts and components should be made of polymer material, because the advantage of polymers against metallic solutions outweigh. The requirements, polymer materials have to comply, are a high thermal resistance, the resistance against oil, a low tendency to creep and a high bending fatigue strength. Within the framework of the diploma thesis the bending fatigue strength of polyamide 66 (PA 66) and polybutylenterephthalate (PBT) should be tested. The results of different conditioned materials, like the dehydrated condition or the oil-gas-conditioned state, should be compared at elevated storage temperatures (120°C). To measure the bending fatigue strength a new fatigue test station was constructed, on which real parts could be tested under conditions which are similar to their application in compressors. The results of the tests should be plotted in Wöhlerdiagrams.