Five cases of pulmonary histiocytomas are presented (four "endobronchial" and one "pulmonary"). They occurred in two children, and three adults over a five year period. Our center has a catchment of 1 million inhabitants. The possible nature and diagnostic possibilities are discussed. The prognosis is good in young people with this disease, which, in principle, does not differ from the same proliferating histiocytic and fibroblastic disorder arising elsewhere. The histological diagnosis was based upon characteristic and consistent morphological features, common to all cases.