AIM:To review the present studies on early diagnosis ofcolorectal cancer.METHODS:The detective rate for early cancer is 1.7%-26.1% based on various statistical data,with much higherdetective rate in endoscopy.Since early cancer meansinvasion involved in the mucosa or submucosa,thediagnosis can only be made when the invasive depth isidentified.Pathological tissue materials from bothsurgical operation or endoscopic resection are suitable forearly cancer evaluation.RESULTS:Incidence of polyp malignancy is 1.4%～20.4%.The various constitutive proportion of polyps mayexplain the different rates.Malignant incidence is higherin adenomatous polyps,that for villous polyps can reach21.3%-58.3%.Type Ⅱ early stage of colorectal carcinomais rarely reported in China,It is shownd that majority ofthem were not malignant,most of type Ila being adenomaor hyperplasia,and lib being inflammatory and IIc mightbe the isolated ulcers.The occurrence of malignancy oftype Ⅱ is far lower than that of polypoid lesion,in China,the qualitative diagnosis and classification of neoplasmgenerally adopted the WHO standard,including surgicalexcision or biopsies.There is impersonal evaluationbetween colorectal pre-malignancy and cancer.Theformer emphasizes the dysplasia of nuclei and gland,while the latter is marked with cancer invasion.Diagnosisof early stage colorectal cancer in endoscopy is made withtoo much caution which made the detective rate muchlower,Mass screening for asymptomatic subjects andfollow-up for high risk population are mainly used to findthe early stage colorectal cancer in China.Fecal occultblood test is also widely made as primary screening test,galactose oxygenase test of rectal mucus(T antigen),fecal occult albumin test are also used.The detective rateof colorectal cancer is 24-36.5 per 105 mass population.CONCLUSION:Although carcinoma associated antigen inblood or stool,microsatellite DNA instability for high riskfamilial history,molecular biology technology for stooloncogene or antioncogene,telomerase activity andexfoliative cytological examination for tumor marker,areutilized,none of them is used in mass screening by now. AIM: To review the present studies on early diagnosis of colorectal cancer. METHODS: The detective rate for early cancer is 1.7% -26.1% based on various statistical data, with much higher DETECTION rate in endoscopy. Early early cancer means invasion involved in the mucosa or submucosa , thediagnosis can only be made when the invasive depth is is identied. Pathological tissue materials from bothsurgical operation or endoscopic resection are suitable forearly cancer evaluation .RESULTS: Incidence of polyp malignancy is 1.4% ~ 20.4%. various constitutive proport of polyps mayexplain the different rates . Malignant incidence is higher in adenomatous polyps, that for villous polyps can reach 21.3% -58.3%. Type II early stage of colorectal carcinoma is rarely reported in China, It is shownd that majority of the were not malignant, most of type Ila being adenomaor hyperplasia , and lib being inflammatory and IIc mightbe the isolated ulcers.The occurrence of malignancy of type Ⅱ is far lower than that of polypoi d lesion, in China, the qualitative diagnosis and classification of neoplasmgenerally adopted the WHO standard, including surgicalexcision or biopsies. is is impersonal evaluationbetween colorectal pre-malignancy and cancer. The article emphasizes the dysplasia of nuclei and gland, while the latter is marked with cancer invasion.Diagnosisof early stage colorectal cancer in endoscopy is made withtoo much caution which made the detective rate muchlower, Mass screening for asymptomatic subjects andfollow-up for high risk population are mainly used to findthe early stage colorectal cancer in China. Fecal occultblood test is also The widely made as primary screening test, galactose oxygenase test of rectal mucus (T antigen), fecal occult albumin test are also used. The detective rate of colorectal cancer is 24-36.5 per 105 mass population. CONCLUSION: Although carcinoma associated antigen in blood or stool, microsatellite DNA instability for high risk histamistory, molecular biology technology for stooloncog ene or antioncogene, telomerase activity andexfoliative cytological examination for tumor marker, areutilized, none of them is used in mass screening by now.