Thyroid hormones play a m1ajor role in our bodies; they affect the regulation of other hormones. The aim of this work is to assess pulmonary functions in hypothyroid patients. Forty hypothyroid patients and twenty healthy volunteers were subjected to:1-History taking.2-Clinical examination.3-Assessment of pulmonary functions using electronic spirometer to measure: VC, FVC,FEV1, PEFR, FEF25 ,FEF50 ,FEF75 , FEF25-75 ,MVV,FEV1%.4-Thyroid profile was done for hypothyroid group.The results of this work showed that hypothyroidism causes mainly a restrictive pattern in the pulmonary functions, but sometimes mixed or even pure obstructive pattern may be present.Patients controlled on thyroxine showed results better than those of uncontrolled patients.