Asthmatic symptoms characteristically come and go, with a time course of hours to days, resolving spontaneously with removal from the triggering stimulus or in response to antiasthmatic medications. Patients with asthma may remain asymptomatic for long periods of time. Report of symptoms that occur or worsen at night is a feature of asthma. The subjects recruited directly from the department of pulmonary medicine based on the inclusion and exclusion criteria. Minimum 60 subjects needed for the study. The parameters of lung volumes (SVC, FVC, FEV1, FEV1/FVC%, FEV1/SVC%) recorded by ATS standardized MEDISOFT® spirometry. FEV1/SVC diagnosed obstruction in 33 out of 41 patients (80.49%) compared to FEV1/FVC which diagnosed obstruction in 16 out of 41 patients (39.02%) with statistical significance (p=0.000). The discrepancy is 41.47%.