Background: Guidelines for post resection surveillance of colorectal cancer recommend a collection of the patient's history and physical examination, testing for carcinoembryonic antigen (CEA), and colonoscopy. No consistent guidelines exist for the use of abdominal computed tomography (CT) and position emission tomography (PET)/PET-CT. The goal of our study was to describe current trends, the impact of oncologic follow-up on guideline adherence, and the patterns of use of nonrecommended tests. Methods: We used Texas Cancer Registry-Medicare-linked data (2000-2009) to identify physician visits, CEA testing, colonoscopy, abdominal CT, and PET/PET-CT scans in patients ≥66 years old with stage I-III colorectal cancer who underwent curative resection. Compliance with guidelines was assessed with a composite measure of physician visits, CEA tests, and colonoscopy use from start of surveillance. Results: In patients who survived 3 years, the overall compliance with guidelines was 25.1%. In patients seen regularly by a medical oncologist, compliance with guidelines increased to 61.5% compared with 8.8% for those not seen by a medical oncologist regularly (P <.0001). The use of abdominal CT and PET/PET-CT increased from 57.5% and 9.5%, respectively, in 2001 to 65.8% and 24.6% (P <.0001) in 2006. Patients who saw a medical oncologist were more likely to get cross-sectional imaging than those who did not (P <.0001). Conclusion: Compliance with current minimum guidelines for post treatment surveillance of colorectal cancer is low and the use of nonrecommended testing has increased over time. Both compliance and use of nonrecommended tests are markedly increased in patients seen by a medical oncologist. The comparative effectiveness of CT and PET/PET-CT in the surveillance of colorectal cancer patients needs further examination. © 2013 Mosby, Inc. All rights reserved.