The current problems of malignant growth biology, in particular the molecular background of the specific microenvironment of tumor cells and their interaction with stromal cells, which mediates the behavior of tumors and the tumor-host interrelationship were the subject of the International Conference entitled "Tumor Hypoxia and Malignant Progression", a meeting held at the House of Scientists of the NAS of Ukraine in Kyiv, Ukraine, October 1 st to 4 th , 2008. The meeting was hosted by the R.E. Kavetsky Institute of Experimental Pathology, Oncology and Radiobiology of the NAS of Ukraine (IEPOR), and was dedicated to the 90 th Anniversary of the National Academy of Sciences of Ukraine. Over the last years, scientists have focused extensively on the problem of tumor hypoxia as a factor promoting tumor progression. It is known that hypoxia, as a constituent of the tumor cell microenvironment as well as aerobic glycolysis, are important features of malignant tumors. The direct correlation between high levels of hypoxia and tumor aggressiveness has been shown in numerous studies. Therefore, hypoxia is regarded as a factor of unfavorable prognosis. There is a number of different methods available for the evaluation of the level of hypoxia, some of which are being applied in the clinical setting. The stimulating impact of hypoxia and hypoxia-associated proteins on neoangiogenesis and vasculogenesis in tumor tissue has been demonstrated. Several studies have focused on the development of agents capable of blocking hypoxia-associated signaling pathways and vasculogenesis in tumor. Recently, the direct association between hypoxia-dependent signaling pathways and expression of factors that mediate inflammation in tumor tissue, in particular tumor-associated macrophages has been shown. To summarize, a better understanding of the relationships between hypoxia-associated signaling pathways, metabolic peculiarities and inflammatory factors that positively influence tumor progression may elucidate not only how the aggressive tumor phenotype is formed but also may assist in the development of new approaches for the treatment of cancer patients.