3608 Background: The National Quality Forum has endorsed the use of adjuvant chemotherapy in stage III colon cancer, yet a substantial treatment gap exists in the United States. Our objective was to evaluate the contribution of postoperative complications on the use of adjuvant therapy after colectomy for cancer. Methods: Patients from the National Surgical Quality Improvement Program and the National Cancer Data Base who underwent colon resection for cancer were linked (2006-2008). The association of complications on adjuvant chemotherapy use was assessed using multivariable regression models. Results: From 140 hospitals, 2368 patients underwent resection for stage III colon adenocarcinoma. Overall, 36.8% (871/2,368) patients were not treated with adjuvant therapy, of which 47.8% (416/871) had documented severe comorbidities or advanced age (≥80) as the reason for no adjuvant therapy receipt. Of the remaining 455 patients, 21.3% (97/455) had ≥1 serious complication that could account for adjuvant therapy omission. The remaining 41.1% (358/871) patients did not have a documented reason for not recieving adjuvant therapy. Complications associated with adjuvant therapy omission were abscess/anastomotic leak (OR 1.91, 95% CI 1.02-3.59), renal failure (OR 7.16, 95% CI 1.92-26.79), prolonged ventilation (OR 7.92, 95% CI 2.97-21.13), re-intubation (OR 5.69, 95% CI 2.13-15.18), and pneumonia (OR 4.05, 95% CI 2.07-7.90). Abscess/anastomotic leak was associated with a 28-day delay in time to adjuvant chemotherapy (73 vs. 45 days, p<0.05). Superficial surgical site infection did not decrease adjuvant therapy receipt but delayed the time to its use (57 vs. 44 days, p<0.05). The occurrence of postoperative sepsis was associated with a 15-day delay to adjuvant chemotherapy (60 vs. 45 days, p<0.05). Conclusions: Serious postoperative complications explained nearly one quarter of the adjuvant chemotherapy treatment gap among stage III colon cancer patients. Postoperative complications affect treatment utilization and should be considered when calculating adherence with the Stage III adjuvant therapy for colon cancer measure. Judging provider performance using quality metrics is challenging without clinical data.