The sinuses are air filled cavities within the facial skeleton. There are 4 groups. The frontal, located with the bones of the forehead, the maxillary, located within the cheek bones, the ethmoid, a honeycomb like arrangement of cells located between the two eyeballs and the sphenoid located deep in the nasal cavity almost in the center of the head. The maxillary sinus is the largest of all the sinuses. The maxillary sinus is also the commonest sinus to get infected. Most acute infections of the sinuses respond to antibiotics but some may persist despite medical treatment. Options for treatment of sub-acute or chronic (long standing) sinusitis are several and are usually customized to the patient. Irrigating the sinus to wash out the infection is one of the options. Antral wash out (AWO) or lavage is a minor surgical procedure that aims at irrigation the maxillary sinus. This is usually performed for persistent infection of the maxillary sinus. It involves making a small puncture on the wall of the maxillary sinus that separates it from the nose. Through this puncture a small cannula is entered into the maxillary sinus. Through the cannula the sinus cavity is irrigated. The returning fluid comes of the natural maxillary sinus opening. The procedure is very straight forward and takes less than 5 minutes. The procedure can be performed in the clinic under local anesthesia. Nasal preparation is done by placing co-phenylcaine patties in the nose for about 10 minutes. Following that the lateral wall of the maxillary sinus infiltrated with 2% lidocaine and 1:80000 epinephrine. The maxillary wall is then punctured with a trocar and canula. In a well prepared patient, there is usually no pain. Once the cannula is in, the irrigation is started. Keep the mouth open to allow the returning fluid out. The process can then, if indicated repeated on the other side. It is not uncommon to experience palpitations due to anxiety and the anesthetic infiltration but generally the procedure is well tolerated. No specific post-operative care is necessary. Some analgesics for pain may be prescribed. Minor bleeding may occur.