Background: Although Lung is the primary target organ involvement in corona virus disease-19 (COVID-19), post-covid lung pathology and its impact on lung functions is still uncertain. Material and methods: Prospective multicentric study conducted during May 2020 to September 2021, to find pulmonary function assessment in post-COVID-19 recovered pneumonia cases irrespective of their symptoms, included 600 cases in symptomatic and asymptomatic group and subjected to inclusion and exclusion criteria. All cases were subjected to Spirometry analysis. Statistical analysis was done by using chi-test. Results: In Spirometry assessment of post-COVID-19 pneumonia cases at 12 weeks post discharge form hospital, abnormal lung function in 77.5% post covid-19 pneumonia cases; restrictive pattern was predominant type and documented in 43.33% cases, normal lung functions were documented in 22.5% cases. In age and gender assessment in normal and abnormal lung functions assessment, statistically significant association in males 90/150 versus females 45/315 [p<0.00001]; and in age of population in study cases as below 50 years 110/300 versus above 50 years 25/165 [p<0.0001]. CT severity score has shown negative impact on lung function after recovery at 12 weeks post-discharge; cases with score <8, 8-15 and >15 documented normal and abnormal lung functions as in 36/54, 60/80 and 39/331 respectively of total 600 study cases [p<0.00001]. Duration of illness has associated negative impact on lung function; <7 days, 8-15 days and >15 days of onset of symptoms documented normal and abnormal lung functions in 108/132, 22/168 and 5/165 cases respectively [p<0.00001]. Low oxygen saturation at entry point has negative impact on overall outcome on lung function; cases with oxygen saturation <75%, 75-90% and >90% observed as normal and abnormal lung functions in 92/18, 35/135 and 6/314 cases respectively [p<0.00001]. Timing of BIPAP/NIV has significant association in attaining normal lung functions after post-COVID19 pneumonia recovery; cases received BIPAP/NIV at entry point <1 day, 3-7 days and after 7 days of hospitalization were documented normal and abnormal lung functions in 30/150, 40/35 and 5/50 cases respectively [p<0.00001]. Conclusions: Pulmonary functions abnormality in post-COVID-19 pneumonia cases has been documented and should be assessed cautiously to have successful treatment outcome. Restrictive lung disease is the predominant lung function impairment in post-COVID 19 recovered lung pneumonia cases. Age above 50 years, male gender, Diabetes, High CT severity, longer duration of illness, proper timing of initiation of BIPAP/NIV therapy, has documented significant impact on post covid lung functions at 12 weeks assessment.