Objective To evaluate the application of immunochemical fecal occult blood test for colorectal cancer screening in a gastroenterology clinic. Methods Total 512 outpatients received immunochemical fecal occult blood tests and colonoscopy for screening of colorectal cancer from January 2009 to October 2010 in Gastroenterology Clinic of Peking Union Hospital.The application of occult blood test was retrospectively evaluated using colonoscopy and pathological examination as the gold standard. Results Among 512 patients,203 were found positive for immunochemical fecal occult blood. According to the colonoscopy and histological study,115 patients had polyps,9 with high-grade dysplasia and 21 with colorectal cancer.The sensitivity,specificity,positive likelihood ratio and negative likelihood ratio of fecal occult blood to detect colorectal adenomatous polyps was 42.8％,60.9％,1.09 and 0.93,respectively.And those for detection of colorectal cancer and high-grade dysplasia were 76.6％,62.5％,2.05 and 0.37,respectively.Conclusions Immunochemical fecal occult blood test was useful in the screening for colorectal tumors among gastroenterology clinic patients.More large-scale prospective studies are needed to establish a screening model for colorectal tumors.