Mutations of the human p53 gene are of importance in the development of cancer. Perhaps 50% of all human cancers contain a mutation in the p53 oncogene and many laboratories are investigating mutations at this locus. In an effort to centralize and standardize the information regarding human p53 mutations, we have created a computerized database that contains information about DNA sequence alterations for > 3000 p53 mutants. Information on the cancer type, the origin of the cells, the specific mutation, the amino acid change, the literature citation, and other data are provided for each mutant. We have also produced a software package for the analysis of the p53 database. Routines have been developed for the analysis of single-base substitutions, including programs to (a) determine whether two mutational spectra are different, (b) display the number of mutations and mutable sites in each exon, (c) determine whether mutations show a DNA strand bias, (d) determine the frequency of transitions and transversions, (e) display the number and kind of mutations observed at each base in the coding region, (f) perform nearest neighbor analysis, and (g) display mutable amino acids in the p53 protein. The software runs only on IBM-compatible machines with MS-DOS. The software and p53 database are freely available via the Internet, using the remote file transfer protocol. These programs simplify the analysis of the rapidly increasing body of information about p53 mutations. The programs permit facile comparison between different p53 data sets, as well as the identification of mutational patterns that may be of importance to experimenters studying the mechanisms of mutation and the etiology of cancers.