Fatigue life prediction of structures whose natural frequencies lie near the frequencies of the input loading requires the stress results from dynamic analyses. These analyses can be performed in either the time or the frequency domains depending on the nature or the loading. This presentation will outline the approaches available for fatigue life prediction using Altair OptiStruct and APA product, nCode DesignLife for both time and frequency based dynamic analyses. The strengths, weaknesses and assumptions of each approach will be presented, along with typical applications enabling the user to select the proper technique for their particular use case.