Bortezomib is a proteasome inhibitor that can be effective in the treatment of refractory and relapsed multiple myeloma. Recently, severe pulmonary complications associated with bortezomib therapy have been reported in Japan. Because bortezomib has not yet been approved for general use in Japan and is imported by attending physicians on the request of patients, The Japanese Society of Hematology and The Japanese Society of Clinical Hematology sent urgent questionnaires to the councilors of both societies to explore the situation and the details of pulmonary complications associated with bortezomib therapy. Clinical details were available for 46 patients who had been treated with personally imported bortezomib in Japan. Seven patients (15.2%), including 3 who died from respiratory failure, showed complications definitely or probably caused by bortezomib. Of the 7 patients, 6 had a prior history of stem cell transplantation (SCT), whereas only 14 of 39 patients without lung injury had received SCT treatment (P = .033, Fisher exact test). Multivariate analysis revealed that the concomitant use of corticosteroids might reduce the risk of lung injury (P = .024; odds ratio, 0.055) and that a previous SCT might increase the risk (P = .042; odds ratio, 13.140). We summarized these data from questionnaires for a limited Japanese cohort and therefore do not know the precise incidence of lung injury linked to fatal progression. Thus, future verification concerning this matter is warranted after the approval of bortezomib for use in Japan. Clinicians should be aware of the possibility of severe pulmonary complications associated with bortezomib therapy.