Tumor hypoxia is a serious and enduring problem for traditional solid tumor therapies. Many scientists continue to explore methods to improve or exploit tumor oxygenation; more recently, scientists have also focused on altering the molecular effects of hypoxia. These cellular responses to hypoxia and the resulting physiological effects, with a focus on angiogenesis, invasion/metastases, apoptosis, and metabolism, are examined. Recent efforts to mitigate or exploit these molecular pathways alone and in conjunction with traditional therapies are also explored. Current experimental results suggest that targeting multiple downstream molecular pathways of hypoxia will be more effective than targeting a single molecular pathway of hypoxia, and careful planning is necessary in scheduling these new therapies to optimize their effects in combination with traditional therapies.