In this randomized, controlled trial, the use of pirfenidone in patients with idiopathic pulmonary fibrosis led to a slower rate of loss in forced vital capacity than the use of placebo. Idiopathic pulmonary fibrosis is a chronic, progressive, and fatal lung disease that is characterized by irreversible loss of lung function. 1 Although periods of transient clinical stability may be observed, continued progression of the disease is inevitable. 2 The prognosis is poor, with a 5-year survival rate that is similar to the rates for several cancers. 3 – 6 Pirfenidone is an oral antifibrotic therapy that has been evaluated for the treatment of idiopathic pulmonary fibrosis in three phase 3, randomized, controlled trials. One of these trials was conducted in Japan and involved 275 patients. It was followed by two multinational studies, Clinical Studies . . .