Correlated studies on the cellular kinetics in association with the nuclear ploidy pattern and the pathological morphology of advanced colorectal cancers have been carried out using DNA-RNA cytofluorometry with an AO stain. The results showed that advanced colorectal cancers could be separated into the 3 distinct groups that follow: group I, involving a diploid cell population; group II, a polyploid cell population; and, group II', an aneuploid cell population. The group I type was located in the entire colorectal region, where as groups II and II', were in the sigmoid and rectum. Three groups were mostly Borrmann type 3 cancers, and the gross pathological classification was not found to be related to the ploidy pattern.