TNFalpha plays a role in the pathogenesis of septic shock, inflammatory diseases, autoimmune diseases, graft rejection reaction, acute, and chronic respiratory inefficiency among others. Its activity depends on the type of target cells and different regulating factors, but the effect of biological activity is conditioned by specific receptors such as p55 (type I, TNF R55) and p75 (type II, TNF R75). The aim of the study was to answer the following questions: 1) Is it possible to apply elements of non-linear dynamics to assess the level of expression of TNF, TNFRI, TNFRII genes in tumor cells, pathologically unchanged tissue and metastatically changed lymph nodes? 2) Is theoretically anticipated variability of cytokine and its receptors in colorectal carcinoma cells and the immediate vicinity justified in the developed mathematical model? The research material--specimens taken from tumor, unchanged tissue and metastatic lymph nodes--were histopathologically and molecularly analysed. Results of the molecular research were used to develop a mathematical model using the basic studies on the theory of chaos and biological system modelling.