There seems to be a lot of overlap between these two specialists. After all allergies can cause problems routinely treated by ENT doctors, including sinusitis and rhinitis. So which doctor should you see? If you keep in mind the fact that an ENT deals with disorders of the ear, nose, and throat, you can guess that he won't take care of your eyes. Anyone suffering from conjunctivitis along with a sinus problem should probably see an allergist. It also seems logical that if you have a chronic sinus issue that hasn't resolved with medication or surgery the source of the problem may be allergies. Unfortunately, there's no clear cut answer to this question. It may be hit and miss for some patients but if you've hit a dead end with your ENT perhaps it's time to consider seeing an allergist.