The international guidelines on chronic obstructive pulmonary disease (COPD) recommend inhaled bronchodilators for maintenance treatment of the disease. These drugs include β2-agonists and muscarinic antagonists, which are both available as short-acting agents (to be used as needed for dyspnea) and long-acting agents. To the latter belong salmeterol and formoterol (long-acting β2-agonists) and indacaterol, vilanterol and olodaterol (very long-acting β2-agonist) as β2-agonists, and tiotropium, aclidinium and glycopyrronium bromide as long-acting muscarinic antagonists. The efficacy and safety of indacaterol and glycopyrronium as monotherapies has been demonstrated in several controlled trials. However, in some patients with moderate-to-severe COPD, symptoms are poorly controlled by bronchodilator monotherapy; in these cases the addition of a second bronchodilator from a different pharmacological class may be beneficial. Here we review the evidence from published randomized trials concerning the efficacy and safety of the once-daily fixed-dose dual bronchodilator combining indacaterol and glycopyrronium.