PurposeTo study the relationship between the nuclear DNA contents and colorectal cancer.MethodsThe nuclear DNA contents were measured by automatic image analysis technique in 21 cases with normal colorectal mucosa,and in 32 cases with colorectal cancer. ResultsThe DNA index(DI), proliferation index(PI), S %, ＞ 5C% and detection rate of aneuploidy were significantly higher than those of normal colorectal mucosa group. DNA polidy pattern of colorectal cancer group were type Ⅲ and Ⅳ, but that of normal colorectal mucosa group was only type Ⅰ . ConclusionsThe DNA content was related to the degree of differentiation of tumor, size of tumor, situs of tumor and prognosis, not related to age or sex. Measuring nuclear DNA content in colorectal cancer was useful for diagnosing colorectal cancer, understanding the biological characteristic, assessing patient prognosis.