ATP-dependent chromatin remodeling complexes are specialized protein machinery able to restructure the nucleosome to make its DNA accessible during transcription, replication and DNA repair. During the past few years structural biologists have defined the architecture and dynamics of some of these complexes using electron microscopy, shedding light on the mechanisms of action of these important assemblies. In this paper we review the existing structural information on the SWI/SNF family of the ATP-dependent chromatin remodeling complexes, and discuss their mechanistic implications.