The SWI/SNF family of complexes utilizes the energy of ATP hydrolysis to remodel chromatin structures, thereby allowing transcription factors to gain access to DNA. Recent studies suggest that these remodelers also participate in other DNA metabolic reactions such as replication and viral integration, and even in control of cell growth and tumor suppression. The SWI/SNF remodelers can be classified into at least two distinct subfamilies: one includes human BAF (also known as hSWI/SNF-A) and yeast SWI/SNF; the other comprises human PBAF (hSWI/SNF-B) and yeast RSC. Although both types of complexes have similar subunit composition and chromatin remodeling activity in vitro, they cannot replace each other during transcription mediated by specific activators. Thus, each remodeler probably works with a specific set of activators during gene activation. The availability of distinct types of remodelers can allow cells to regulate expression of a specific group of genes by modulating the activity of corresponding remodelers.