Background/Aims: 7lorectaI cancers are the most common cancers of the gastrointestinal system. A significant relationship was detected between the metastasis and tumor angiogenesis of colorectal cancer. The aim of the present study was to investigate the association between some cytokines and tumor stages. Additionally, association between VEGF gene polymorphisms and colorectal cancer was studied.Methods: In this study, we measured serum IL-18, IL-2, VEGF, endothelin (ET), and nitric oxide (NO) levels in 44 patients With colorectal cancer and 44 healthy controls. Also we investigated VEGF G634C (rs2010963) and VEGF C936T (rs3025039) polymorphisms of VEGF gene in these groups by using a PCR-RFLP method. Data were analyzed statistically. Results: Serum levels of IL-18, VEGF, IL-2 and NO were significantly higher in patients with colorectal cancer when compared to controls (p<0,05). Serum ET levels were found to be similar in colore ctalsancer patients aactlealthy controls When we compared are the two subgroups constituted by tumor stages (Stage 1-2 and Stage 3-4) with each other, serum VEGF levels were found significantly higher in stage 3-4 group than stage 1-2 group (p<0,05). No significant difference was found between subgroups with regard to other parameters. We found that investigated VEGF G634C and VEGF C936T polymorphisms were not associated with the severity of colorectal cancer. (P= 0.228 for VEGF G-634-C; P= 0.484 for VEGF C-936-T) Conclusion: In the future, serum levels of IL-18, VEGF, IL-2 and NO may be a useful marker for diagnosis of patients with colorectal cancer. Additionally we consider. that serum VEGF levels can be used as a tumor marker to predict prognosis of cancer. However, larger studies with long-term follow-up are necessary to clarify this hypothesis. On the other hand, there is necessity for the new studies for determination of association between VEGF gene polymorphism and colorectal cancer.