A method for microscopical observation and quantification of corneal neovascularization in the living mouse is described. Measurements of the corneal vasculature were made on still-mode video-pictures of the cornea. The validity of the method was shown by the high correlation between the morphometric measurements and computerized values on the same vessel structures. The method was applied to describe the neovascular response of heat-killed tumour fragments implanted into corneal pockets. The neovascular response that was observed in some corneas was dependent on the distance from the edge of the pocket with heat-killed material to the nearest vessel loop. The pocket area was vascularized only if this distance (measured the 3rd day after implantation) was less than 0.70 mm. Resorption of heat-killed tissue occurred in corneas without any neovascular response and it was not altered by penetration of vessel into the cornea. The described method proved to be suitable for studying the neovascularization induced by corneal pocket implants.