Worsening breathless in a patient with severe chronic obstructive pulmonary disease (COPD) is a common diagnostic and management challenge in primary care. A systematic approach to history-taking and examination combined with targeted investigation of pulmonary, cardiovascular, thromboembolic and systemic causes is essential if co-morbidities are to be identified and managed. Distinguishing between heart failure and COPD is a particular challenge as symptoms and signs overlap. In low and middle income countries additional priorities are the detection of infections such as tuberculosis and human immunodeficiency virus (HIV). Clinicians need to be alert to the possibility of atypical presentations (such as pain-free variants of angina) and less common conditions (including chronic thromboembolic pulmonary hypertension) in order not to overlook important potentially treatable conditions. (C) 2013 Primary Care Respiratory Society UK. All rights reserved.