&NA;The profile of serum glycoproteins is altered in malignancy with a relative increase in acute phase reactant proteins. A prospective study has been performed to investigate three sugar moieties (hexose, hexosamine and sialic acid) of these glycoproteins in the serum of large‐bowel cancer patients as a possible guide to recurrence, and to compare these three variables with carcinoembryonic antigen (CEA). The three variables indicated the presence of colorectal cancer in over 65 per cent of 107 cancer‐bearing subjects. Furthermore, the appearance of metastatic disease was associated with abnormalities in these variables in 10 of 11 patients, and appears more accurately reflected than with CEA. However, the three variables and CEA are cumulative in their value for predicting recurrent cancer. Monitoring of acute phase reactant proteins may therefore be of potential clinical benefit for monitoring of colorectal cancer patients at high risk of recurrence.