PURPOSE: To obtain a medicinal agent for preventing and/or treating vasa sanguinea retinae occlusion such as vena centralis retinae occlusion.

CONSTITUTION: This vasa sanguinea retinae occlusion-preventing and treating agent contains a urokinase precursor capable of administering the urokinase precursor at a daily dose of at least 4500 units. The preventing and treating agent comprises at least 4500 units of the urokinase precursor packed in a container. Two stages or more of the improvement in visual acuity was recognized by intravenously injecting the urokinase precursor at a daily dose of at least 4500 units, but systemic complications such as bleeding tendency was not recognized.