Cognitive-behavioral treatment (CBT) protocols for panic disorder (PD) consist of a set of interventions that often includes some form of breathing retraining (BR). A controlled outcome study was designed to assess the necessity of BR in the context of a multicomponent CBT protocol. To accomplish this, patients with PD (N = 77) were randomly assigned to receive CBT with or without BR or to a delayed-treatment control. The main study hypothesis was that patients receiving BR would display a less complete recovery relative to the other active-treatment condition given that BR appears to be a more attractive (but less adaptive) option for some patients. Some data suggested that the addition of BR yielded a poorer outcome. However, findings were generally more consistent with treatment equivalence, questioning whether BR produces any incremental benefits in the context of other CBT interventions for PD.