Fecal occult blood test (FOBT) plays an important role in community because it could be applied widely with the low cost and available in screening and diagnosis colon-rectal tumor diseases. Aim of the study was to investigate the association and availability of FOBT in diagnosis colon-rectal tumor diseases through coloscopy process. The results indicated that the mean age is 47.2 + or - 15. The ratio female/male is 1.13/1. The prevalence of FOBT(+) in colon - rectal cancer, colon-rectal polyp is 81.8 percent, 43.5 percent respectively. The sensitivity, specifictiy, positive predictive value and negative predictive value of FOBT in detecting colon - rectal cancer are respectively 76.7 percent, 81.8 percent, 15.4 percent, 98.8 percent and in detecting colon - rectal polyp are respectively 43.5 percent, 75.8 percent, 17.1 percent, 92.1 percent. In conclusion, FOBT is really important in detecting and screening colon - rectal cancer.