Dipeptidyl peptidase IV(DPPIV) or CD26 is a widely expressed ectopeptidase with functions in immune response such as the activation of T lymphocytes. It is expressed in the colon mucosal epithelium only when this becomes malignant. The aim of our study is to ascertain the soluble DPPIV/CD26 levels in the serum of patients with colorectal carcinoma, compared with the levels in healthy individuals. From an accrual of 70 healthy individuals and 99 patients diagnosed with colorectal adenocarcinoma, the levels of soluble DPPIV/CD26 were defined by colored enzymatic spectrophotometric response on the Gly-Pro-Paranitroaniline substrate. The patients diagnosed with colorectal cancer have a higher CD26 level than healthy subjects (p<0.05). Of these patients, those with metastatic colorectal disease have a significantly higher soluble CD26 level (p<0.01). It has also been found that patients with high LDH (lactatodeshidrogenase) and CEA (carcinoembrionary antigen) levels show higher CD26 levels (p<0.01) than patients with normal levels of such carcinoma markers.