Gene amplification is one of the characteristics of cancer cells. In vitro studies suggested that alterations of the TP53 gene might be responsible for gene amplification. We have examined the presence of TP53 mutations and looked for cytogenetic evidence of gene amplification in a series of 79 primary colorectal carcinomas. Other parameters such as the pattern of cytogenetic alterations, microsatellite instability, tumor site, and histological staging were also considered. A multiparametric study supported by statistical analyses suggests the existence of two major pathways of colorectal carcinogenesis. No relationships could be established between the presence of TP53 alterations and gene amplification.