Nitrosoureas belong to the group of alkylating agents, and are increasingly used in the treatment of brain malignancies, due to their excellent penetration through the hemo-meningeal barrier. Since 1976, pulmonary toxicity from nitrosoureas has emerged as a significant problem, especially with BCNU, and 72 cases are available in the literature for review. While it is difficult to ascertain the exact prevalence of nitrosourea lung (estimate range between 1 and 20%), it is now clear that a direct relationship exists between cumulated exposure to the nitrosourea, and the likelihood of developing pulmonary toxicity. The clinical picture is that of a diffuse, severe fibrosis with hypoxemia. Histopathology, available in 55 reports, showed diffuse bland fibrosis. The outcome is poor with 67% of the patients dead by the time of publication. While we feel that corticosteroids should be tried for any possible beneficial effect, they seem to be of limited help.