Inflammatory bowel diseases (IBDs), ulcerative colitis and Crohn's disease are lifelong disorders, characterized by the chronic inflammation of all or part of our digestive tract. Cytokines have an essential role in the pathogenesis of IBDs, because they control the inflammatory response, and the disequilibrium of pro-inflammatory/anti-inflammatory cytokines may lead directly to tissue destruction. Histopathologically, these diseases are characterized by the extent and the distribution of mucosal architectural abnormality, the cellularity of the lamina propria and the present cell types, but these features frequently overlap. We performed a prospective study, which included 46 patients diagnosed with ulcerative colitis (UC) (gender ratio 25 males/21 females, mean age 44.8 years) and 30 subjects, with similar demographic characteristics, which were selected from the patients investigated for other digestive disorders, unaffected by UC. Serological investigations were performed by quantitative determination of IL-17, IL-13, and CRP using ELISA sandwich technique. We have achieved significantly higher concentrations of IL-13, IL-17 and CRP in the serum of patients with UC, compared to the control group. We have found in our study correlations between ulcerative colitis activity and serum levels of interleukins, IL-13 and IL-17. Because IL-17 serum levels were significantly correlated with the disease severity and only cytokine had a significantly statistic correlation with high serum levels of CRP in UC patients, IL-17 can be considered an important progress inflammation marker of this disease.