The formation of new blood vessels, uncontrolled cell expansions and invasions are the common feature of cancer, neovascular inflammatory and ocular diseases, such as age-related macular degeneration (AMD). Short interfering RNA (siRNA) and short-hairpin RNA (shRNA) have recently helped extend our understanding of the mechanisms regulating angiogenesis and tumor developments. Moreover, the early success of these tools has reinforced the therapeutic hopes of preventing endogenous or exogenous gene translation. In vivo experiments using several animal tumor models and human pre-clinical trials augured many benefits to control protein expression and cell signaling. The high specificity of siRNA and shRNA to target a protein is crucial to design a new generation of therapeutic agents. At the present, several investigations are focused on the understanding of both gene function and the proof-of-concept for siRNA-mediated anti-angiogenesis. Taken together, in vitro and in vivo studies shed light on the efficiency of siRNA as a new alternative therapeutic agent.