EPH receptors and their ephrin ligands constitute the largest sub-family of receptor tyrosine kinases (RTKs) and are components of cell signaling pathways involved in animal development. The ability of the EPH/ephrin guidance system to position cells and modulate cell morphology underlies their various roles in development. In addition, EPH signaling plays an important role in oncogenic processes observed in several organs. These receptors are involved in a wide range of processes directly related with tumorigenesis and metastasis, including cell attachment and shape, migration, and angiogenesis. Accordingly, deregulation of EPH expression and signaling activity could be crucial for the tumorigenic process. This review focuses on EPH receptors' roles in oncogenic transformation and tumor progression.