Nonfunctioning pituitary lesions represent a subset of pituitary adenomas that do not manifest with clinical features of hormone hypersecretion. Because of their indolent nature, their diagnosis is elusive, often resulting in presentation after the tumors have grown large enough to cause compressive symptoms. Although they are clinically silent, the various subtypes correspond to the predominant cell line of origin and therefore are biochemically distinct from one another. This article reviews the biochemical, clinical, and histopathologic features of each of these subtypes. A rubric is provided for diagnostic work-up of these lesions and the management options available to the treating clinician.