Idiopathic Pulmonary Fibrosis has been reported worldwide.The aim of this work is to study the role of Bronchoalveolar lavage cellular analysis in assessment of severity of idiopathic pulmonary fibrosis.Twenty cases were selected from the Chest department Kasr El-Aini Hospital inpatient. All patients were subjected to full history taking, clinical examination, HRCT, PFT, ABG, Echocardiography, FOB and BAL cellular analysis.There was statistically significant negative correlation between neutrophils and FEF25-75% (P-value 0.003) while insignificant negative correlation with PCO2, PO2, SO2, 6 MWT, FVC%, FEV1%, PASP. Also there was statistically significant positive correlation between macrophages and SO2 (P-value 0.042) and FEF25-75% (P-value 0.020) while insignificant positive correlation between macrophages and PO2, SO2, FVC% and FEV1%.