Objective To study the clinical characteristics of hereditary nonpolyposis colorectal cancer (HNPCC). WT5”HZMethods Ten kindreds of HNPCC in South Zhejiang area were analyzed. ResultsWT5”BZ Among the 10 families, 27 persons had colorectal cancer with age ranging from 19 to 71(average 45 3 years),74 percent of cases being diagnosed before the age of 50. The total of the colorectal cancer foci in 27 cases were 37, 40 percent of focis located proximal to splenic flexure, 30 percent of cases had multiple primary colorectal cancer, among which 14 8 percent of cases had synchronous multiple primary colorectal cancer, 18 5 percent of cases had metachronous multiple primary colorectal cancer. Thirteen cases died during follow-up of 1～23 years, 14 cases were still alive during follow-up of 1～28 years. KG2Conclusion HNPCC has definite charactistics that are of much help to early diagnosis.