Tenascin-C is a multidomain large extracellular matrix glycoprotein composed of six monomers. The size of tenascin-C monomers (180-250 kDa) varies as a result of an alternative splicing of the fibronectin repeats at the pre-mRNA level. For the first time we applied bioinformatic and molecular modeling procedures, for detailed analysis of the organization of tenascin-C and we performed bioinformatic analysis of tenascin-C gene. We detected the presence of heat shock protein 33 in the tenascin-C N-terminal domain that may suggest its role in the protein-protein interactions and stress response. The number of fibronectin type III-like repeats and epidermal growth factor-like repeats were corrected to 15 and 14, respectively. Using polyactylamide gel electophoresis, RT/PCR analysis and microarrays data, we showed the higher level of tenascin-C in the human tumor tissues: brain, intestine and breast. These results suggested a new role of tenascin-C as the potential tumor marker and drug target.