BACKGROUND Hypothyroidism is a condition resulting from inadequate thyroid hormone secretion from the thyroid gland due to the structural and functional impairment. Many patients with hypothyroidism present with dyspnoea. Hypothyroidism causes a restrictive pattern of lung disease due to respiratory muscle weakness, hypoxic alveolar hypoventilation and decrease in maximal breathing capacity. Aims and Objectives-The objective of the present study is to evaluate spirometry in patients with hypothyroidism, supplement them with levothyroxine according to protocol and reassess their spirometry after three months and compare the two sets of spirometry parameters. MATERIALS AND METHODS An uncontrolled clinical trial with supplementation of levothyroxine for a period of four and a half months to the newly diagnosed hypothyroid patients was carried between February 2017 and October