Patients with silicosis having variable degrees of respiratiory impairment were evaluated using the american thoracic society criteria for respiratory impairment including integrative cardiopulmonaryexercise testing (CPX), to study the different cardiopulmonary responses to exercise testing in silicosis patients and its role in disability evaluation. Resting ventilatory pulmonary functions are poor indicators of the patient symptoms and working capacity when measured directly by exercise test.