Objectives: Ÿ To grade the severity of Diffuse Parenchymal Lung Diseases by HRCT and Correlate the HRCT Severity with Spirometry indices. Ÿ To predict the performance of carbon monoxide diffusion capacity (DLCO) for associated HRCT ndings in the detection of diffuse parenchymal lung diseases. Conclusion And Results A Cross sectional study was conducted at radiology department of tertiary healthcare hospital in Central India for 2 years study period in patients suffering from diffuse lung disease. The results are summarised below: Ÿ The highest frequency of age was 50-60 years (36.7%) followed by 60-70 years age (33.3%) and 40-50 years age (13.3%). Mean age was 57.83 year. Ÿ Maximum patients were male (70%). Ÿ Maximum patients had breathlessness (86.7%), cough (76.7%) and chest pain (56.7%). Ÿ Only few patients had fever (20%), history of smoking (30%), h/o infection (13.3%) and systemic disease (16.7%) Ÿ Maximum patients had UIP (46.7%) followed by NSIP (23.3%) and RB ILD (13.3%). Ÿ Mean FVC was 66.13 l, mean FEV1 was 56.47 %, mean FEV1/FVC was 0.81% and mean DLCO was 49.67 mL/min/mm Hg. Ÿ Maximum patients had restrictive (76.7%) followed by normal (20%) and obstructive (3.3%). Ÿ Normal interpretation (6) was seen in DSIP (1), SCLERODERMA-ILD (2) and UIP (3). Obstructive interpretation (1) was seen only in RB ILD (1). Restrictive interpretation was seen higher in NSIP (7), RB ILD (3) and UIP (11). Comparison between interpretation and diagnosis was showed statistically signicant results. Ÿ Total score was higher in restrictive (30.87) followed by obstructive (20) and normal (19.5). Comparison between interpretation and total score was showed statistically signicant results. Ÿ Comparison between interpretation and spirometry prole (every parameter) showed statistically signicant results. Ÿ Higher total score was showed in POST COVID FIBROSIS NSIP (36), SARCOIDOSIS (32), NSIP (31) and UIP (29.86). Comparison between interpretation and total score was showed statistically signicant results. INFERENCE: The patients included in the study were distinguished patients with diffuse parenchymal lung diseases from those with normal lungs, correlated closely with both 2D analysis and visual quantitation. This study shows that cough, restrictive, FVC, DLCO have statistically signicant correlation with total HRCT score in patients with diffuse parenchymal lung diseases. FCV correlated the best with HRCT. DLCO also showed correlation with HRCT in patients with diffuse parenchymal lung diseases.