THE FACT that adenomas and carcinomas of the colonic mucosa tend to be mul t ip le and to coexist has become increasingly well substantiated. The re is also considerable evidence that the mucosal adenoma is the lesion which precedes carc inoma of the colon in a highly significant p ropor t ion of cases. Surgeons experienced in this field recognize the l imitat ions of pa lpa t ion of the intact colon in the detect ion of small lesions and in disclosing soft, sessile tumors as large as several centimeters. Meticulous roentgenologic studies by air contrast and high-voltage technics after the use of a bar ium enema will demonst ra te many of these tumors, bu t cannot be depended u p o n to reveal all, par t icular ly if the lesions are less than 1 cm. in diameter. Hence, at the time of laparotomy, the surgeon who seeks to eradicate these lesions is ob l iga ted to take addi t ional reasonable measures to deal with probable undetected neoplasms. I t was to fill this need that the technic of colotomy and coloscopy for direct visualization of the entire mucosa of the colon was devised.