An aged Guernsey cow entered the Stange Memorial Clinic on June 30, 1950, showing blindness in one eye and enlargement of the frontal sinus. The cow was examined and the cornea of the left eye was found to be ruptured, the entire eye being inflammed. The frontal sinus was enlarged and the left horn stub showed a hemorrhagic discharge. On diagnosis of a suppurative sinusitis of the right frontal sinus with abscessation and involvement of tissues around the left eye, it was decided that enucleation of the eye and trephining of the frontal sinus for drainage be performed.