Exercise dyspnea is a common symptom of restrictive lung diseases. Not only from the clinical perspective but also from the pathophysiological point of view, restrictive lung disorders represent a very heterogeneous group of diseases. Exercise testing is mandatory because pulmonary function tests at rest are not reliable for the diagnostic evaluation and functional characterisation of these patients. Cardiopulmonary exercise testing (CPET) with measurement of gas exchange is the favoured tool. It is an excellent method to investigate exercise dyspnea, describe altered physiological response to exercise and characterise the involved organ systems heart, lung and muscle. This paper addresses the pathophysiology of restrictive lung diseases and the principles of cardiopulmonary exercise testing, discusses case reports and assesses the clinical value of CPET in patients with restrictive lung disease.