Surgical resection of the primary tumor for patients who present with incurable stage IV colorectal cancer is controversial. National practice patterns have not been described. We evaluated the use of primary tumor resection in patients presenting with stage IV colorectal cancer. Patients with stage IV colorectal cancer diagnosed between 1988 and 2000 were selected from the Surveillance, Epidemiology, and End Results database. Patients undergoing primary tumor resection were analyzed on the basis of sex, race, year of diagnosis, and the anatomical site of the primary tumor. We compared the survival of resected and nonresected patients. A total of 17,658 (66%) of the 26,754 patients presenting with stage IV colorectal cancer underwent primary tumor resection. Patients with resected disease were more likely to be young (mean age of 67.1 vs. 70.3 years) and to have right-sided tumors (75.3%, 73.0%, and 45.6%, respectively, for right, left, and rectal; P < .001). In all age groups, patients undergoing resection had higher median and 1-year survival rates (colon: 11 vs. 2 months, 45% vs. 12%, P < .001; rectum: 16 vs. 6 months, 59% vs. 25%, P < .001) when compared with patients who did not undergo resection. Most patients who present with stage IV colorectal cancer undergo resection of the primary tumor. The proportion of patients undergoing resection depends on patient age and race and the anatomical location of the primary tumor. The degree to which case selection explains the treatment and survival differences observed is not known. Further investigation of the role of surgery in the management of incurable stage IV colorectal cancer is warranted.