Rigid sigmoidoscopy is beneficial as it detects rectal or distal sigmoidal lesions very efficiently and precisely. But it also has some complications, e. g. rectal injury, rectal perforation or transient bacteremia. In this prospective study, 800 cases were collected and divided into two groups. In group I, 400 O.P.D. symptomatic cases were chosen randomly and in group II 400 cases registered for routine physical examination were picked up. The positive detection rate was 7% in group I versus 2% in group II. The lesions detected in group I are 15 cases of cancer, 7 cases of polyp, 4 cases of irradiation proctitis, 2 cases of ulcerative colitis and 1 case of pseudomembranous colitis. Only 8 polyps are found in group II. The routine sigmoidoscopy is mandatory for symptomatic patients but it is not cost-effective for routine check-ups. The stool occult blood is the best screening test for detecting colorectal lesions. For routine physical examination, stool occult blood test is safe and easy to perform. If the stool occult blood test is positive, then further examinations will be necessary.