Abstract: Gastrointestinal carcinoma is one of the top eight malignant diseases in term of inci-dence or cancer deaths in China. The most critical element of improved survival for cancer pati-ents is early diagnosis. To find an accurate,simple,rapid and conveneint test is necessary. Weset up a methods,using electrophoresis and enzyme labeled antibody staining assay with threemonoclonal antibodies against colorectal and gastric cancer.The mass screening by this assay wasperformed in 1801 cases.The results showed:thirty two cases were positive in 1801 persons,thepositive rate was 1.8%.After GI endoscopic and histological examinations,the final diagnosiswere:one case of early gastric cancer.19 cases of pre-malignant lessions,5 of them were colonadenomas,12 were chronic atrophic gastritis,1 was chronic supcrficial gastritis with dysplasia,1was multiple diverticulosis in an old man and 7 cases were non-malignant diseases,The palsepositive rate was 0.3%. After follow-up for more than one year no cancer was found in theother negative 1750 cases.This preliminary results show that this method may be useful in massscreening and early diagnosis of gastrointestinal carcinoma.