Objectives: Tumor markers and biochemical parameters were investigated in patients suffering from colon cancer and in volunteer healthy persons. Design and Methods: Biochemical analyses of erythrocyte enzymes and serum values for series of established tumor markers were conducted for 40 patients diagnosed with colon cancer, before and after chemotherapy, and 29 healthy volunteers between 2008 and 2009. Results: Activities of catalase and carbonic anhydrase were lower in sick than healthy groups (p<0.05) before and after chemotherapy, while alkaline phosphatase and creatinine were increased. The patients with colon cancer showed significant (p<0.05) elevation of CRP, fibrinogen, CA125, AFP, and decrease in ferritinin, before but not after therapy. Conclusion: The results obtaining from this investigation can be useful for colon cancer risk assessment.