The SWI/SNF complex participates in the restructuring of chromatin for transcription. The function of the yeast SWI/SNF complex in the remodeling oi a nucleosome array has now been analyzed in vitro. Binding of the purified SWI/SNF complex to a nucleosome array disrupted multiple nucleosomes in an adenosine triphosphate-dependent reaction. However, removal of SWI/SNF left a deoxyribonuclease I-hypersensitive site specifically at a nucleosome that was bound by derivatives of the transcription factor Gal4p. Analysis of individual nucleosomes revealed that the SWI/SNF complex catalyzed eviction of histones from the Gal4-bound nucleosomes. Thus, the transient action of the SWI/SNF complex facilitated irreversible disruption of transcription factor-bound nucleosomes.