This paper is written in answer to a number of requests which have been made for a detailed description of the technic for ethmosphenofrontal operation. On previous occasions I have discussed various aspects of this operation. In 1922 Dr. Robin Harris and I1 discussed "Gross and Microscopic Pathology in Twenty-Three Consecutive External Ethmo-Sphenoid Operations;" in 1927 Dr. Sam H. Sanders and I2 described "Interesting Observations in More Than One Hundred External Ethmo-Frontal Operations;" in 1930 I3 presented a moving picture of the procedure, and in 1935 I4 published a paper entitled "The Indications for the External Ethmo-Spheno-Frontal Sinus Operation." At no time, however, has an illustrated description of the entire procedure been placed in print by myself or my associates.
The procedure is that of Jansen,5 Knapp6 and Lynch,7 with some modifications which have gradually been made.
The indications for this procedure are different, depending on whether the condition is