Uncontrolled unilateral glaucoma developed in the right eye of a 24-year-old woman. It was caused by the diffuse growth of a nonpigmented nevus of the iris into the anterior chamber angle. Histologically, the nonpigmented nevus cells in the angle were distinguishable from a proliferation of corneal endothelium. Clinically, there was no heterochromia, and a tumor was not suspected as the cause of the glaucoma.