Bortezomib (Velcade(®)), a proteasome inhibitor, was launched for the treatment of relapsed or refractory multiple myeloma in Japan in December 2006. Prior to approval in Japan, high incidence (15.2%) and mortality (6.5%) of bortezomib therapy-related lung disorders were reported with private import treatment. Therefore the Velcade Lung Disorder Panel (the Panel) was established and the cases have been reviewed. A total of 3,556 patients, including 823 post-marketing surveillance (PMS) patients, have received bortezomib since April 25, 2009. The incidence of lung disorders associated with bortezomib therapy was 2.33% (3.77% in case of PMS). The panel reviewed the detailed information of 70 cases and classified the CT and X-ray images as follows: (1)Interstitial pneumonia; diffuse alveolar damage pattern, hypersensitivity pneumonia pattern and others (2)Vascular hyperpermiability; (non-cardiogenic) pulmonary edema pattern and capillary leak syndrome-like pattern (3)Hypoxia. These post-marketing data showed that the incidence of lung disorders in Japan was lower than expected based on private import data.