Introduction: Respiratory disorders are a class of major public health problems confronting the world for over many years. It is one of the important reasons for mortality in many countries every year . COPD (chronic pulmonary disease and Asthma , together with pneumonia are third most common cause of death. pulmonary function tests are used in clinics to assess the extent of the deterioration in lung functions, to predict the prognosis, to decide on treatment and to evaluate the response to treatment and evaluating lung function in the preoperative period and in health research. Material and Methods: 60 individuals were enrolled in this observational study. They were categorized into three groups. a) Healthy subjects b) Asthma patients, c) COPD patients. FEV1, FVC, FEV1/FVC were measured by spirometer. Results: Data were analyzed by student ANOVA and Bonferronis post hoc test- P value < 0.05 can be considered statistically significant The mean ± SD levels of FVC in asthma is (2.21 ± 0.69), COPD (2.37 ± 0.81) and (2.71 ± 0.54) in normal healthy controls. The levels of FEV1 in respiratory diseases like Asthma, COPD are ( 1.93 ± 0.57), (1.93 ± 0.67) and (2.38 ± 0.41) in normal healthy controls. The ratio between the FEV1/FVC in Asthma, COPD and normal healthy individual are ( 88.01 ± 4.64, 81.11 ± 4.77, 90.71 ± 5.08) respectively. In Asthma, COPD the FVC values are increased with statistically insignificant of (p>0.05) when compared with normal healthy individuals however the FEV1 levels of Asthma, In COPD FEV1/FVC ratio is decreased with highly statistical significant with (p<0.001) in comparison to normal healthy controls. However in asthma the FEV1/FVC values are decreased with non significant when compared with normal healthy individual. Discussion: Pulmonary function test (PFT) are used in clinics to asses the extent of the deterioration in lung functions, to predict the prognosis, to decide on treatment and to evaluate the response to treatment and in evaluating lung function in the preoperative period and in health research. There are various factors that influence the PFT, the most important ones being sex, age, race and height causes change in PFT values. From the present study, it states that there is an inverse relation between FVC and FEV1 in Asthma and COPD when compared with normal healthy controls.If the levels of FVC are increased then there is a decreased level of FEV1 . in Asthma and COPD there is no variation in FVC but decreased levels in FEV1 is observed when compared to the normal healthy individuals. Conclusion: Finally the above hypothesis conclude the importance of FVC and FEV1 levels plays an important role in identification of several various pulmonary disorders, however further studies should be adopted for the detailed aspects of the study.