Gemcitabine is an anti-cancer drug known to be safe and effective for pancreatic or biliary tract cancers, but lung injury is also known to be a rare side effect that sometimes becomes severe. Here we report seven cases of lung injury during gemcitabine treatment. Drug-induced lung injury was suspected in all cases. The male: female ratio was 5:2, and the average patient age was 71. Four had pancreatic cancers and three had biliary tract cancers. Gemcitabine had been administered an average 5.9 times at a dose of 1,141 mg. Patients showed a diffuse or patchy shadow mainly in the lower lung on computed tomography examination. Grades of adverse events were greater than 3 in all cases. Three patients died of the lung injury. Five cases had pulmonary emphysema, 2 had metastatic lung tumor as underlying pulmonary lesions, and these were assumed to have been important risk factors for drug-induced interstitial lung injury during gemcitabine treatment.