We retrospectively examined by flow cytometry the DNA ploidy pattern in tissue blocks from 25 primary colon adenocarcinomas and their lymph node and liver metastases. Intratumoral heterogeneity was present in 22% of primary tumors and 21% of metastatic liver deposits. Intertumoral heterogeneity, measured between the primary tumor and its lymph node and liver metastases, was 0% and 20%, respectively. Of 24 patients who underwent successful resection of their liver metastases, 8 neoplasms had uniformly diploid DNA content, while 16 tumors had aneuploid DNA pattern in either the primary tumor, the metastases, or both. Five-year survival was better in the diploid group (38% vs. 7%, P = 0.10 by log rank analysis). Three of eight patients in the diploid group remain free of disease, while all 16 patients with aneuploid cell populations have died of recurrent disease.