Idiopathic pulmonary fibrosis is a chronic progressive lung disease with poor prognosis. The IFIGENIA trial showed that antioxidative therapy with N-acetylcysteine versus placebo for patients under treatment with prednisone plus azathioprine significantly slowed the deterioration of pulmonary function after 12 months. A number of other drugs have recently been evaluated in large multicenter placebo-controlled trials. Etanercept, interferon-γ, bosentan, ambrisentan, imatinib, and sildenafil did not show efficacy. The antifibrotic active ingredient pirfenidone is the first drug approved for the treatment of adult patients with mild to moderate idiopathic pulmonary fibrosis in the European Union. Approval was based on the results of 4 randomized, placebo-controlled clinical trials including more than 1,100 patients. Pirfenidone slowed the decline in lung function and reduced the risk of disease progression. Side effects include gastrointestinal discomfort, skin reactions, including photosensitivity, and rarely increased liver enzymes.