Twenty-one patients had a concurrent splenectomy with resection of colorectal cancer between 1970 and 1988. These were matched individually with disease control patients based on age, sex, site of tumor, Dukes stage, tumor differentiation, and date of the operation. Significantly more patients in the splenectomy group (n = 11) developed postoperative infective complications than in the control group (n = 4) (McNemar test: P = 0.03). Five-year overall actuarial survival was 45 percent in the former group and 59 percent in the latter (log rank test: chi-squared = 1.07; P = 0.24). Similarly, five-year disease-free survival in 17 patients with Dukes B and C cancers who had curative resections did not differ between the groups (log rank test: chi-squared = 0.08; P > 0.25). These results suggest that splenectomy with resection of colorectal cancer increases the risk of postoperative sepsis and does not influence long-term survival. The infrequency of concurrent splenectomy at resection of colorectal cancer may not overcome Type II error.