Purpose: The risk of malignancy after solid-organ transplantation is well-documented. However, the incidence and specific risk for colorectal adenocarcinoma, though previously proposed, has been difficult to calculate. We reviewed the University of Wisconsin transplant database for all cases of colorectal adenocarcinoma to assess the risk of this malignancy, as well as the need for improved screening in this population. Methods: The transplant database was queried using diagnosis codes for colorectal adenocarcinoma to configure a list of eligible patients. Exclusion criteria included: age less than 18 years at the time of transplant, diagnosis of colorectal cancer or patient death less than 12 months post-transplant, and pre-transplant history of colorectal cancer or proctocolectomy. Statistical analysis determined the incidence, survival and age-specific considerations for this population. Results: A total of 5603 kidney, liver, pancreas, or combination transplants were eligible for analysis from 1966 through 2004. We identified 40 cases of colorectal adenocarcinoma. Twenty-five of these cases (62%) occurred in kidney transplant recipients, 13 after liver transplant, and 2 after combination kidney-pancreas. Twenty-seven patients (68%) diagnosed with cancer have died, 12 of metastatic disease. The mean survival post-cancer diagnosis was 1.72 years. These results were compared to the National Cancer Institute SEER database for colon and rectal cancer. The current age-adjusted incidence based on year 2000 census data is 0.053% (52.9/100,000). The incidence in the transplanted cohort is 0.71% (40/5603). Five year survival post cancer diagnosis is 64.1% in the general population (SEER) vs. 30.7% in the transplanted population. The SEER median age at diagnosis of colorectal adenocarcinoma is 72.0 years. The average age at cancer diagnosis after transplant was 57.5 years (32.4 - 78.2), and 11 patients (27%) were diagnosed at or before age 50. In the U.S. population, the incidence of colorectal adenocarcinoma below the age of 50 is 0.0055% (5.52/100,000) compared to 0.20% (11/5603) in the transplant population. In this under 50 cohort, average time from transplant to cancer diagnosis was 9.8 years. Conclusion: The incidence of and five year survival after diagnosis of colorectal adenocarcinoma in transplant recipients is markedly different from the general population. Patients often present with advanced disease and are diagnosed at a younger age. With current screening guidelines, over 25% of at-risk patients would not be screened. We propose modifying these guidelines to allow earlier detection of colorectal cancer in this population.