A follow-up study with special reference to nucleolarorganizer region-associated protein (AgNOR) and DNA ploidy was conducted in 83 consecutive cases of colorectal cancer patients who underwent radical surgery at the people's Hospital, Beijing, from 1982 through 1986. Counting on the mean number of AgNOR showed a predominant difference between the tumor tissue (9.796 +/- 3.670) and normal mucosa (2.937 +/- 0.812), (P < 0.001). With regard to the tumor differentiation, the number of AgNOR was paralleled with the degree of malignancy of the tumor, 8.178 +/- 2.864 for well differentiated tumors, 10.086 +/- 3.940 for moderately differentiated tumors and 11.577 +/- 2.824 for poorly differentiated ones. Patients with lower AgNOR (< 10) tumor had a prominent survival advantage over those with AgNOR > or = 10 tumor. Particularly when combined with the factors of DNA ploidy and AgNOR, prognosis of patients with diploid tumor and AgNOR < 10 was more favorable than that of those with aneuploid and AgNOR > or = 10 tumor.