Aim: To evaluate the two-dimensional echocardiographic assessment of pulmonary artery hypertension in thyroid dysfunction. Methods: A prospective double blind randomized controlled study was conducted at ARC Hospital, Bhagalpur, Bihar, India for 1 year. Thyroid function tests were done in all cases using Enzyme immunoassay to confirm the presence of hypo or hyperthyroidism. Electrocardiography wasrecorded in all the patients.Chest X-rays were done and examined for roentgenographic signs of pulmonary hypertension, i.e. right descending pulmonary artery diameter of >1.5 cm. 2D-Echocardiography was done in all cases and screened for the presence and severity of pulmonary hypertension. Results: In our study out of the 100 cases, 70(70%) cases were of Hypothyroidism and 30 (30%) cases were ofHyperthyroidism. Unpaired t test is applied. P value is significant if < 0.05 PASP value in patients with hyperthyroidism was 31.06mm Hgwhile that in the patients with hypothyroidism was 27.17mm Hg. Difference between them was comparable. 80% patients with hypothyroidism and 66.66% patients with hyperthyroidism had normal PASP level. While 20% patients with hyperthyroidism had mild and moderate PASP each, only 16.67% with hypothyroidism had mild PASP. The mean PASP by Doppler Echocardiography was 39.52 mm of Hg in the pre-treatment group. And the mean PASP during the follow up (after 10 months) was 31 mm of Hg. Among the patients in the Hypothyroidism group with PAH, the pre-treatment values of TSH and PASP were high andreduced in the follow-up (after 10 months of treatment) Among the patients in the Hyperthyroidism group with PAH, the mean pre-treatment value of TSH was 0.2 and increased to 2.35 in the follow up. Mean PASP value was 42.6 and reduced in the follow-up (after 10 months oftreatment) to 31.7. Conclusion: The PAH secondary to thyroid dysfunctions may be reversed by restoration of euthyroid state, and hence patients have a good prognosis if diagnosed and treated timely. So every patient of thyroid dysfunction should bescreened for PAH, even though further studies areneeded to substantiate this.