This survey reports on 10 case-studies of drug-induced pneumonitis. The drugs under consideration are amiodarone, methotrexate, chlorambucil, sulindac, nilutamide-leuproreline, cyclothiazide, with the possible addition of bleomycin. In each case, one or more bronchoalveolar lavage were carried out and in most cases it was also possible to perform a transbronchoscopic lung biopsy. The results of these tests are analysed in order to ascertain their contribution to diagnosis and prognosis. Regarding diagnosis, bronchoalveolar lavage does not evidence a typical cellular configuration characterizing drug-induced alveolitis. Moreover, transbronchoscopic lung biopsy plays no part in diagnosing this pathology. Both these tests, however, help to eliminate other hypotheses. Regarding prognosis, transbronchoscopic lung biopsy provides no information, unlike bronchoalveolar lavage in which a high rate of neutrophils in the lavage fluid is sometimes associated with the development of pulmonary fibrosis.