Carcinoembryonic antigen (CEA) values in 529 patients treated in two consecutive adjuvant chemotherapy protocols were analyzed to determine if CEA values correlated with disease-free status or prognostic utility. CEA values were evaluated preoperatively, before chemotherapy, at the conclusion of chemotherapy, and during postchemotherapy followup. The sensitivity of CEA for predicting disease recurrence was low; however, any abnormal CEA at the conclusion of chemotherapy and during followup significantly correlated with reduced disease-free and overall survival. A CEA value greater than or equal to 20 ng/ml at the end of chemotherapy or during followup was highly specific and a strongly positive predictor for the presence of metastases. Abnormal CEA values before chemotherapy that became normal at the conclusion of chemotherapy were associated with a significantly reduced recurrence rate. An abnormal CEA value obtained before or after adjuvant chemotherapy is clinically useful and can provide prognostic information.