Tumor microenvironment is contained of non-tumor cells which surround the tumor. Tumor microenvironment is significally different from healthy tissue and because of that surrounding cells can have different function than they would have in healthy tissue. Also, with secretion of cytokines or with direct interaction with surrounding cells, tumor can change its microenvironment. One of the most common cells in tumor microenvironment are macrophages. Tumor associated macrophages (TAM) are cells which are modified by tumor in the purpose of its survival and development. With secreting numerous cytokines and with expressing different receptors and ligands TAM helps tumor by allowing the immune response to be avoided, while it promotes angiogenesis and lymhogenesis and metastasis of tumor. TAMs can also negatively affect on the existing therapies which is why drugs that would inhibit TAM effect and whose basic principles are described in this paper are increasingly being searched for. Tumor microenvironment of every tumor and by that the function of TAM is different and because of that special attention was paid in this paper on TAMs in breast and lung tumors.