Recently, atomic models of the mammalian, fungal and the bacterial fatty acid synthases type I (FAS I) were reported. Now, a wealth of functional data, collected during the last decades, can be embedded into structural frames. But there is more, which remains to be done! Our current considerations are implicitly very much based on a static view onto these proteins. The next step is to include the dynamic processes, which are essential for the function of FAS I. In this perspective, aspects of the current knowledge are reviewed and presented as the basis for the scientific challenges in a new epoch of FAS research.