Key words: cytokines, immune system, cancer. The article is a review of literature on role of cytokines in cancer. Cytokines are important factors in the activation and development of immune response, including responses against tumor cells; however the data in literature is controversial. Cytokines have various roles in the growth of cancers. The mixture of cytokines that is produced in the tumor microenvironment can inhibit tumor development and progression in some conditions or cytokines can promote growth in other conditions, attenuate apoptosis and facilitate invasion and metastasis. There is a particular emphasis on mechanisms of cytokine actions in malignant cells, although they are not sufficiently understood. A more detailed understanding of cytokine-tumor-cell interactions provides opportunities for a better understanding of cytokine biology, and role of immunoregulation in the microenvironment of tumor, but more advanced research is necessary in this direction.