Four new cases of punctate thymic calcification in infants with untreated Langerhans' cell histiocytosis (LCH) are added to the four previously reported cases. All cases were shown on CT scans; plain films were rarely diagnostic. Pathologic correlation remains elusive since the usual biopsies of the LCH have been on skin or bone biopsies. A single prior pathologic study of the thymus in untreated LCH showed microscopic calcospherites. The thymic punctate calcific densities in patients with LCH may represent further accretion so that the calcospherites become macroscopic. The finding of such punctate calcific densities in an enlarged thymus of an infant with skin or bone or lung disease is strongly suggestive of LCH.