INTRODUCTION Thrombosis of the cavernous sinus is a very rare condition. In 1902, Dwight and Germain1 stated that only 182 cases had been reported, and in 1918, Smith2 estimated the number reported as less than 300. Only eight cases were found by us in 50,000 of the surgical records of the Johns Hopkins Hospital from 1889 to 1919. This is only one case for every 6,250 patients. We are including in this report four other cases: two of these were on other services3 in the Johns Hopkins Hospital; and we are indebted to Surgeon-General Ireland, United States Army, for the privilege of reporting two other cases (Cases 11 and 12) which were seen by Dr. Chisolm while in the army during 1918 and 1919. REPORT OF CASES Case 1.—History.—A colored laundress, aged 40, was admitted to the Surgical Service of the Johns Hopkins Hospital, May