There is currently controversy regarding the use of serum carcinoembryonic antigen (CEA) in the follow-up of colorectal cancer. This article reviews the most recent clinical data regarding CEA and discusses the rationales for its use in the follow-up of colorectal cancer. The patterns of colorectal cancer recurrence and their variable association with CEA elevation are presented. The contributions of the new imaging modalities, including radiolabeled antibodies, are reviewed and information on the prognosis following resection of recurrences is provided. A practical approach to colorectal cancer recurrences is suggested in two algorithms.