Abstract: The DNA content in 15 colorectal cancers from 7 patients was measured by flow cytometry on paraffin-embedded specimens to see if this parameter supported common or independent origins for such synchronous and metachonous tumors. In 4 of the 7 cases, the tumors within each colon had identical DNA indices, and in three cases both tumors from the same colon differed with respect to DNA content. Four（26.7%） of 15 tumors were aneuploid. The remaining 11 tumors were diploid. These findings suggest a common origin for the cases who had identical DNA content, it may arise as translumenal metastases from an initial single lesion The others are compatible with multiple origins.