Background: Management of stage III colon cancer (SIIICC) frequently focuses on cancer-specific survival, yet overall survival and adverse events also impact the net clinical benefit of cancer management strategies. Furthermore, there are evidence gaps surrounding overall survival among elderly patients. Methods: A retrospective cohort analysis examined all-cause survival among incident SIIICC patients within Surveillance, Epidemiology, and End Results (SEER)-Medicare data for patients diagnosed between 2004 and 2005 with follow-up through 2007. Medicare parts A&B (without Medicare HMO) was required to avoid missing claims data. Patients were censored due to death, end of simultaneous enrollment in Medicare parts A&B, or enrollment in an HMO. Patient descriptive characteristics and outcomes were examined using chi-square and t-tests; adjusted survival analyses used Cox proportional hazards regressions. Results: There were 4,985 SIIICC patients, of whom 1,033 (20.7%) were diagnosed with VTE following SIIICC diagnosis. African-Americans, urban residents, and those with higher CCI scores or VTE in the year before SIIICC diagnosis were more likely to have a VTE following their cancer diagnosis. VTE patients had significantly higher mortality (48.75% vs. 43.05%, p < 0.01). Multivariate analyses controlling for clinical and demographic factors showed that patients with VTE were 26% (CI: 14.1%-39.6%) more likely to die. Other significant predictors of mortality included older age, poor performance status at baseline, CCI =2+, treatment with chemotherapy or monoclonal antibodies. Conclusions: VTE following diagnosis of stage III colon cancer diagnosis is a significant predictor of death. Among elderly Americans diagnosed with stage III colon cancer, the increased hazard of death due to VTE was 26%.