A large number of Monel 400 steam generator tubes may be subjected to low cycle fatigue because of the particular location of the thermal plate. A low cycle fatigue analysis method, simulating the deformation response of structural component elements due to irregular load history, was applied to predict stress-strain behavior and then fatigue life of the Monel 400 steam generator tubing. The experiments revealed that under worst loading conditions (maximum displacement, with a tube locked in the thermal plate), the specimens failed due to mechanical fatigue in a period corresponding to three to five times the expected service life of a steam generator. Standard internal coil eddy current inspection techniques were not successful in detecting the cracks that had initiated in the Monel tubes in the region of the modeled tubesheet. This made the experimental and analytical fatigue life prediction work even more valuable.