The maxillary sinus (MS) is the most common sinus to be affected by disease. It varies greatly in shape, size, position and pneumatization, not only in different individuals, but also in different sides of the same individual.Several disease processes can involve the maxillary sinus, such as infective, odontogenic and neoplastic. In simple cases, a standard uncinectomy and middle meatal antrostomy (MMA) may be sufficient for visualization and clearance of disease but despite this, a drawback still exists in both external and endoscopic intranasal surgical procedures. Compromise of the inferior turbinate (IT) and nasolacrimal duct (NLD) is often unavoidable.According to the anatomy of maxillary sinus (MS) and the nature of diseases originated from MS assessed with multi-angled telescopes, including 30,45 and 70 telescopes, with kinds of curved instruments, there are still some areas which cannot be viewed and handled.Such critical areas as the inferior, lateral, anterior wall, zygomatic recess, alveolar recess and prelacrimal recess (PLR) of maxillary sinus are difficult to approach. For this reason other approaches are needed like canine fossa approach (CFA), prelacrimal recess approach (PLRA) and medial maxillectomy approach.