&NA;Of 340 patients with histologically proven colorectal carcinoma, hepatic metastases were diagnosed in 90 (26 per cent), in 50 at the time of initial surgery (synchronously) and in 40 during the postoperative follow‐up (metachronously). At the time of initial surgery, plasma carcinoembryonic antigen (CEA) levels were markedly elevated in patients with synchronous metastases and normal or only moderately elevated in those with metachronous metastases. During follow‐up, CEA levels in the entire group of patients with metastases remained normal in 8 per cent and rose in the remainder: very quickly in 85 per cent and slowly in 15 per cent. Hepatic metatases were diagnosed by strict scintigraphic criteria in 70 per cent of patients and were suggested by liberal criteria in the remainder. During follow‐up, hepatic metastases progressed in the scintigraphic image from those defined by liberal to those diagnosed by strict criteria. In two‐thirds of the patients, liver scintigraphy proved to be superior to the CEA test in diagnosing hepatic metastases by strict criteria; in the majority of the remainder of patients, the CEA test, particularly in cases with a pattern of fast increase of CEA in plasma, suggested metastases before a definite diagnosis could be made by liver scintigraphy. In only 3 per cent of the patients neither liver scintigraphy nor the CEA test were indicative of metastases. Thus, the two diagnostic modalities, when combined, could attain a sensitivity of 97 per cent, when patients with persistently rising CEA levels and concomitant liver lesions defined by the liberal criteria were grouped with those for whom scintigraphy was unequivocal.