It is now generally accepted that both the structure and function of a number of specific transcriptional factors, including p53 (1), are subject to redox regulation in cells in which these factors are expressed. The present chapterdescribes methods for the analysis of redox changes in the structure of p53 and the effect of redox modulation on binding of p53 to a DNA consensus sequence. In addition, methods are described for studying the effect of redox perturbations of cells on the functioning of p53 in the cell cycle and in apoptosis. By studying the effect of redox agents on p53, we have concluded that p53 is subject to structural redox modulation and that this modulation affects the functional ability of the protein to bind to DNA, to cause cell cycle arrest, and to trigger apoptosis.