&NA;Based on data from many clinical studies and programs, guidelines are presented for application of the flexible fiberoptic sigmoidoscope in the management of the surgical patient. The flexible fiberoptic sigmoidoscope has proved to be an instrument of extraordinary capability in detecting colorectal neoplasms with yields being two or three times greater than those of the rigid sigmoidoscope in the symptom‐resolution, polyp and cancer surveillance patient categories. In addition, the practical advantages of the narrow diameter, flexibility, and length of the fiberoptic sigmoidoscope are readily appreciated when the surgeon finds that he can satisfactorily examine patients with rectal or sigmoid strictures, marked angulations, or contracted lumens in whom a rigid scope would be unsuitable. Data from the authors' comparative study of more than 3000 patients have permitted the development of not only guidelines for the application of the flexible fiberoptic sigmoidoscope but an appreciation of the modified role of the rigid sigmoidoscope and the proper relationship between the flexible fiberoptic sigmoidoscope and the flexible fiberoptic colonoscope. A most important consideration is based on data regarding the site distribution of 400 benign premalignant neoplasms detected in the comparative study. The even distribution of these lesions throughout the terminal 50 cm of colorectum underscores the need to examine as much of the colorectum as possible.