Abstract: n this paper, 90 cases of colorectal carcinoma tissue, 101 cases of remote margin, and 15 cases of normal human colorectal tissues were studied by immunohistochemical staining with McAb PC10 for analysis of the relationship between proliferating cell nuclear antigen (PCNA) index assessment and prognosis of colorectal carcinoma. The results showed that PCNA indices in normal colorectal tissues were 0% positive, but in colorectal cancer tissues and remote mucosa were 100% and 80.2% positive, respectively. The PCNA index, whether high or low, seemed to correlate with the clinical stage; Dukes A and B PC10 scores were much lower than Dukes C and D. PCNA indices in colorectal carcinomas and remote mucosa were related to the progress of disease and the prognosis. After at least three years of follow-up postoperatively, in non-recurrent patients, the average PCNA index in cancer tissues and remote mucosa was 38.8% and 3.5%, whereas in patients with recurrence, metastasis, or death, the PCNA index in cancer tissues and remote mucosa was 67% and 39.8% (P < 0.001). Our study indicates that the PCNA index does not correlate with histological grade; it may be another independent factor in predicting tumor recurrence or identifying patient prognosis.