This chapter discusses common cysts and tumors of the jaws, where epithelial lining of oral cystic lesions may be derived from a variety of sources including residua of epithelium persisting following odontogenesis, from glandular tissue such as salivary and seromucous glands, from the sinonasal tract, and from dermal epithelial tissue. An odontogenic cyst develops from remnants of odontogenic epithelium that may persist in the oral cavity following tooth development. Bone resorption associated with expansion of a cystic lesion gives rise to a radiolucent bony defect. Subsequent increase in osmotic pressure from degenerating cells causes cyst formation. Nevoid basal cell carcinoma syndrome represents a condition of autosomal dominant inheritance remarkable for marked variability in expressivity. The aneursymal bone cyst is a central osteolytic lesion that occurs in either a solitary fashion as a primary lesion or in association with a pre-existing neoplasm such as a central giant cell granuloma, benign fibro-osseous lesion, osteosarcoma, or osteoblastoma.