Preoperative and postoperative plasma carcinoembryonic antigen (CEA) levels in patients with colorectal carcinoma have been reported to correlate with tumour mass and prognosis. The erythrocyte sedimentation rate (ESR) has previously been reported to be elevated in most patients with metastatic carcinoma. In this study of 17 patients with advanced colorectal carcinoma and of nine patients who were disease-free more than three years after resection of their tumour, the plasma CEA and ESR levels demonstrated a close correlation, both in frequency and in degree of elevation, with the disease status. Of nine patients who were disease-free more than three years after resection of their colorectal carcinoma, all except one had plasma CEA levels of less than 20 ng/ml and an ESR less than 20 mm in one hour respectively. The incidence of plasma CEA more than 20 ng/ml and ESR more than 20 mm in one hour in the locally advanced and distant metastases groups, as compared with those patients in the more than three years group, was increased at a level of statistical significance (P less than 0.05). This study showed that the ESR, an inexpensive and simple estimation, may be as effective as the estimation of plasma level of CEA in monitoring the disease status of patients with colorectal carcinoma.