Angiogenesis is a key process for tumoral growth, which has become a main target for anticancer treatments. A wide number of agents targeting both VEGF and its receptor have recently become standard treatments for different tumor types. Unfortunately, most of the tumors become resistant to these agents after few months of treatment. Different mechanisms of resistance to antiangiogenic drugs have been proposed and investigated; some agents demonstrated to be able to restore sensitivity to antiangiogenic drugs by blocking pathways or molecules involved in the resistance in preclinical models. Biomarkers for the prediction of response or resistance to antiangiogenic agents are under evaluation.