Glycosaminoglycans undergo significant structural alterations in cancer, namely in terms of their sulfation pattern and hydrodynamic size. Numerous studies have focused on this issue, and have demonstrated that glycosaminoglycans play a crucial role in cancer growth and invasion. However, the majority of the enzymes involved in glycosaminoglycan alterations have yet to be examined in detail. The present study focused on the expression of chondroitin-synthesizing enzymes in colorectal cancer. Specimens from healthy controls and cancer patients were subjected to RT-PCR analysis after RNA isolation, and to Western blotting after sequential extraction. The results indicated that chondroitin polymerizing factor and glucuronyltransferase gradually increased with cancer stage, and were expressed at much higher levels in adenomas compared to adjacent normal tissue. The opposite profile was obtained for chondroitin synthase I. Chondroitin synthase III was present at low levels in all the samples examined; however, its expression was higher in the samples from the cancer patients than in those from the healthy controls. It can therefore be concluded that, among the various factors regulating the structure of glycosaminoglycans in cancer, the differential expression of chondroitin-synthesizing enzymes is of the most significance.