The operation is based on the following principles: 1. That by preserving the anatomical structure tothe maximum degree. it follows that the function is safeguarded; 2. That operations are limited more by physiology than by anatomy; 3. That in chronic sinusitis drainage, aeration and exenteration are the essentials. It is claimed that these desiderata can be accomplished by the foregoing technique in one operation. Derivatives from the main indications of the trans-maxillary operation are numerous. (l) as a preliminary procedure to the external operation of the frontal sinus; (2) in certain eye complications due to sinusitis, such as orbital cellulitis, retrobulbar neuritis, neur retinitis and optic neuritis; (3) complications of the respiratory system asthma and bronchitis; (4) neuralgias, headaches, and obscure affections of the nervous system. Nasal allergy is a causal factor of great importance in chronic sinusitis and polyposis. Allergic treatment is essential in the post operative period, if the partial return of polyps is, in many cases, to be avoided.