The cystic lesions of the maxillary sinus are not so rare E.N.T. clinic. These include odontogenic cyst, retention cyst, mucocele, pyocele and postoperative cyst. In contrast to rather common odontogenic cyst, retention cyst and postoperative cyst, mucocele and pyocele are extremely rare. Each one case of radicular cyst, retention cyst, postoperative cyst and mucocele is here reported. All cases of cystic lesion were performed Caldwell-Luc operation and confirmed histopathological study. The result was eventful.