Continuous monitoring of neovascular growth in vivo is required for the development and evaluation of drugs acting as suppressors or stimulators of angiogenesis. The cornea assay consists of the placement of an angiogenesis stimulus (tumor tissue, cell suspension, growth factor) into a micropocket produced in the cornea thickness to evoke vascular outgrowth from the peripherally located limbal vasculature. Neovascular development and progression can be modified by the presence of locally released or applied inhibitory factors or by systemically given antiangiogenic drugs. This assay has the advantage over other in vivo assays of measuring new blood vessels only since the cornea is initially avascular. The experimental details of the avascular cornea assay and its advantages and disadvantages in different species are discussed.