Abstract: Objective: To study the different clinical phenotypes between HNPCC and common hereditary colorectal cancer and to provide evidences to recognize the genealogical hereditary cancer of colon. Methods: A total of 22 parentages of HNPCC (A group) which is in line with the Amsterdam standard II or Japanese standard and 20 parentages of common colorectal cancer (B group) were followed- up and analyzed. Results: 1) The ratio of incidence between male and female patients of group A and B was 1.37:1 (41/30) and 1.46:1 (38/26) respectively, with no statistically significant difference(P>0.05). 2) The median age in group A and B was 48 (32~70) and 61 (30~83) years, showing a significant difference between the two groups (P<0.001). The morbidity before 50 years in the groups was 59.2% (group A) and 26.6% (group B), showing an earlier incidence in group A than in group B. 3) The ratio of right hemicolonic cancer in group A and B was 56.9% (29/51) and 29.2% (7/24), with a significant difference (P<0.05). 4) There were 7 cases of multiple cancer in group A, but none in group B. 5)The mean age of onset of the patients in the first, second, and third generation in group A was 64, 56,and 48 respectively, with a tendency of piecemeal juvenescence, but it didn' t occurred in group B.Conclusion: The clinical phenotypes of HNPCC and common hereditary colorectal cancer have many differences, which indicate some different characteristics of heritage between them.