Retinal neovascularization is a major feature of proliferative diabetic retinopathy, which represents a major public health problem, being responsible for more irreversible blindness in persons of middle and older age than any other pathology. The societal burden of ocular neovascularization has prompted extensive research into its mechanisms. The aim of this review will be to briefly summarize the current knowledge regarding the clinical and laboratory findings of diabetic retinopathy. From an investigational view, studies of ocular neovascularization provide important informations, often permitting real-time, serial observations of neovascularization in vivo. This allows investigators to analyse the relevance of specific pathogenic concepts regarding the mechanisms of angiogenesis in vivo. This review will additionally describe current concepts regarding the pathogenesis and treatment of diabetic retinopathy.