Pulmonary function appraisal had long been considered a laborious test for pulmonary disabled patients that necessitate repetitive trials for attaining superlative results. Meticulous interpretation of this test requires good command of basics of respiratory pathophysiology and consequent influences of point and level affected. First piece of knowledge is to be familiar with carrying out the maneuver, however, second is how to interpret the test results. Finally pulmonolgists can symbolize the proper conclusion.