Abstract: Objective To investigate the clinical and pathologic characteristics of younger patients with primary colorectal cancer in China and American treatment centers.Methods A retrospective study was undertaken.Data was collected from 107 patients in abdominal surgery of Fujian Tumor Hospital in China from 2004 to 2008 and 52 patients in general surgery of Cleveland Clinic Florida USA from 2002 to 2006.All the patients with colorectal cancer(CRC)were diagnosed by surgery and histology.Results By comparing younger patients with primary colorectal cancer in Fujian Tumor Hospital in China and Cleveland Clinic Florida USA,we had the following results:in terms of gender,the proportion of males of younger patients with primary colorectal cancer in the Chinese Hospital was 51.4%vs.55.8%in the American Hospital(χ²=0.268,P=0.605＞0.01).In terms of tumor location:17.8% of younger patients in the Chinese Hospital had lesions in the proximal colon,23.1% of younger Caucasian patients in the American Hospital had lesions in the same location;82.2% vs.76.9% had cancers located on distal colorectum(χ²=0.631,P=0.427＞0.01).In terms of age,the average age was 34.55±4.39year in the Chinese Hospital vs.33.60±6.67 year in the American Hospital(t=-0.940,P=0.350＞0.01).In terms of pathology,the proportion of tubular adenocarcinoma in the Chinese Hospital was 77.6% vs.85.1% in the American Hospital,the proportion of mucinous adenocarcinoma was 16.8% vs.10.6%(χ²=1.056,P=0.304＞0.01),the proportion of signet-ring cell carcinoma was 3.7% vs.0%,the proportion of carcinoid was 1.9% vs.2.1%,the proportion of adenosquamous carcinoma was 0%vs.2.1%.In terms of pathological differentiation of tumor,12.4% in the Chinese Hospital vs.8.9% in the American Hospital were highly differentiated adenocarcinoma,76.2% vs.77.8% moderately differentiated,11.4% vs.13.3% poorly diferentiated(Z=-0.624,P=0.532＞0.01).In terms of staging,11.2% in the Chinese Hospital vs.22.7% in the American Hospital were stage I,29.0% vs.45.5% were stageⅡ,53.3% vs.25% were stageⅢ,6.5% vs.6.8% were stageⅣ.(Z=-2.846,P=0.004＜0.01).The different pathological staging distribution of younger patients with primary colorectal cancer in the two treatment centers had statistical significance.Conclusion Although the two treatment centers had no diference in age,sex,anatomical resolution,pathologic characteristics and differenciation,proportion of the Chinese Hospital was more than that of the American Hospital in stageⅢ.In other words,prognosis of younger patients with primary colorectal cancer in the Chinese Hospital may was worse than those in the American Hospital.