Background: Cirrhosis is a condition in which the liver does not function properly due to long-term damage. This damage is characterized by the replacement of normal liver tissue by scar tissue. Objective: The aim of this work is to study the relationship between severity of liver cirrhosis according to the ChildPugh score and pulmonary function tests (namely spirometry and arterial blood gas). Patients and Methods: The study is a cross sectional one, which was carried out on 50 patients admitted in the inpatient wards, or in regular follow-up in the out-patient's clinics of the Gastroenterology Departments, in Al-Azhar University Hospitals between November 2018 and May 2019.They were divided into 3 groups according to Child Pugh Classification (A, B and C). Result: The prevalence of hypoxia was(30%) in all studied groups (50 patients), the hypoxia was present in patients with Child C and Child B (62%) and (29.4%) respectively but none of Child A had hypoxia. It was noted that all pulmonary functions were worst in patients Child class C when compared to other groups. However, patients Child B had also significantly worse pulmonary functions when compared to patients class A. We also showed that pulmonary functions are significantly correlated with synthetic liver function, Child and MELD score. The deterioration of liver functions and rise of patients score is accompanied by worsening of all pulmonary functions. Conclusion: Patients suffering from severe liver cirrhosis and ascites, have significant reduction in (PaO2) and (SaO2) in association with restrictive pulmonary function pattern (up to 100% of patients with massive ascites).