The DNA content was quantitively determined in 30 specimens of colorectal carcinoma including 15 cases of tubular adenocarcinoma (TAC.5 cases each of grade Ⅰ,Ⅱ and Ⅲ respectively) ,5 cases of papillary adenocarcinoma (PAO.5 cases of mucoid adenocarcinoma (MAC) and 5 cases of signet-ring cell carcinoma (SCO),and 5 specimens of norma! colomic nucosa with mi-crospectro-photometry.The average DNA contents of different tissues were as follows:Normal colonic mucosa:13.54The difference of DNA contents of various types of carcinoma with normal mucosa,and that of TAC-Ⅰ and SCC with TAC-Ⅲ,PAC and MAC was statistically very significant (P