Reviewing studies of alterations of theTP53tumor suppressor gene in human breast carcinomas gives cautious optimism aboutTP53alterations as a prognostic marker in this disease. For the time being, breast carcinomas should be screened forTP53alterations at both the protein and gene levels. Improved mutational screening techniques are needed for this purpose. We consider constant denaturant gel electrophoresis, a modification of denaturing gradient gel electrophoresis, to represent such an improvement. With the recent development of the BioRadD GENEsystem, constant denaturant gel electrophoresis screening forTP53mutations can easily be performed on large series of breast carcinomas.