The acute exacerbation of COPD (AECOPD) is a life-threatening clinical situation. This review summarizes the definition of AECOPD, the severity assessment, typical clinical signs and symptoms, and refers to clinical pitfalls of diagnosis and therapy. Important aspects of clinical history and physical examination in severe exacerbations are reported. The necessary accompanying examinations like chest X-ray, blood gas analysis, ECG and echocardiography and their differential diagnosis as well as therapeutic significance are described. The most important lab examinations are summarized and controversial parameters, e.g., procalcitonin, are commented upon. The differentiated need for a microbiological sputum screening is emphasized. The authors place special weight on the essential components of the therapeutic management of severe AECOPD. Practical aspects of uncontrolled oxygen therapy, drug selection, and application form of inhalative acute therapy, dose, and duration of glucocorticoids, the indication for antibiotics, mechanical ventilation, and also opiates are summarized.