Clear-cell tumor of the lung is a rare entity of unknown etiology and histogenesis. This neoplasm typically presents as an asymptomatic, peripheral, sharply rounded mass in the lung, and histologically composed of large cells with a clear cytoplasm rich in glycogen, blended with an abundant network of sinusoid-type vessels. Immunohistochemical and ultrastructural procedures lead to diagnosis. We describe a primary pulmonary clear cell "sugar" tumor observed in a 28-year-old woman, and give a review of the literature. Clinical aspects, differential diagnosis, therapy and histogenetic aspects are discussed.