The purpose of this study was to investigate the incidence of the types of the panoramic innominate lines in panoramic radiographs of the patients who had no pathoses in the maxillary sinus and adjacent bony structures. And all panoramic radiographs were obtained in standard position. And the following results were observed: Panoramic innominate lines were observed various types of vertical lines running across the outer third of the maxillary sinus in all examined panoramic radiographs. And types of them were similar in the right and left side of each patient. The types of the panoramic innominate lines were observed most frequently as concave type(69.3%), followed by convex type(12.5%), flat type(9.0%), uneven type(8.3%), and obliterated type(1.3%) in descending order of frequency. According to the age and sex, convex type was also observed most frequently in all examined radiographs.