The efficacy of pursed-lip breathing (PLB) and diaphragmatic breathing (DB) in the rehabilitation of people with chronic obstructive pulmonary disease (COPD) remains unclear. This review examines the evidence regarding the usefulness of these techniques in improving the breathing of people with stable COPD. The studies included in our review of the literature used either PLB or DB in isolation, contained a clear description of the methods, and used outcomes that were measured with what we considered to be appropriate procedures. Pursed-lip breathing slows the respiratory rate, and evidence suggests that this decreases the resistive pressure drop across the airways and, therefore, decreases airway narrowing during expiration. This decrease in airway narrowing may account for the decreased dyspnea some people experience when using this technique. Diaphragmatic breathing has negative and positive effects, but the latter appear to be caused by simply slowing the respiratory rate. Evidence supports the use of PLB, but not DB, for improving the breathing of people with COPD.