Prostaglandins E1, E2, D2, A1, F1alpha, and F2alpha as well as synthetic chemoattractants and growth factors were tested for their ability to induce the proliferation of new blood vessels in the rabbit cornea. PGE1 showed the strongest neovasculogenic activity attracting new blood vessels in all of the cases. PGE2 was a weaker attractant than PGE1. PGF2alpha induced a less consistent reaction. All implants sequestering PGD2 or PGA1 were negative. Implants sequestering 1 microgram of fibroblast growth factor or epidermal growth factor variably stimulated the proliferation of keratocytes and epithelial cells in vivo. However, none of these demonstrated any vasculogenic activity. A small, but significant neovascularization was observed only in implants sequestering 10 microgram of growth factor per implant. Although active in vitro, nerve growth factor and formylated synthetic peptides were not stimulatory in vivo.