THE OTOLARYNGOLOGIST is occasionally faced with the problem of differential diagnosis and therapy of cysts occurring in the middle one third of the face, maxilla, or palate. The patient's initial symptom is usually a swelling of the cheek, upper lip, floor of the nose, gingiva, or palate; others are asymptomatic and are only detected after roentgenograms of the facial bones or sinuses have been made. In this paper we will discuss primarily the odontogenic and nonodontogenic cysts. Three case histories are appended illustrating the ways in which they can present. There are also a number of other types of "cysts" occurring in this region, which clinically or roentgenographically may pose a differential diagnostic problem, eg, the sinus mucosal and nonsecreting cysts, salivary retention cysts, the cystic and noncalcifying odontomas, ameloblastoma, traumatic bone cysts, and the lesions of hyperparathyroidism, which do not fall within the true definition of cysts (ie, pathological