A retrospective analysis of survival results for colorectal cancer patients in Illinois was performed by the Cancer Incidence and End Results Committee of the Illinois Division of the American Cancer Society. Cancer registry data on 1,774 patients from 63 hospitals were used to investigate whether the preoperative level of serum carcinoembryonic antigen (CEA) was a prognostic indicator of survival for cancers diagnosed between 1976 and 1978. A direct relationship was found between the preoperative level of serum CEA and both the thickness and stage of the tumor at initial diagnosis. For Stage B2/3 colorectal cancer, the actuarial survival curves corresponding to normal, elevated, and markedly elevated CEA levels were significantly different (p less than 0.0001). The five-year survival rates for these patients were 61, 50, and 32 percent, respectively. Similar trends for patients with Stage C2/3 cancer were observed (p = 0.0058). The corresponding five-year survival rates were 44, 30, and 26 percent, respectively. Using a statewide cancer registry system, the analysis suggested that the preoperative level of serum CEA was an indicator of survival in patients with colorectal cancer, independent of the stage of disease at diagnosis.